For the version for the original Delta-Chat manual draft see here.
Dedication: This manual is dedicated for the members of the Sangha of the eight directions, and their devoted followers, and of course given to make use of it by everyone for what ever good and harmless undertakings. Anumodana!
The Sārahārī-Saṅghaṁ-App, email-messenger combination, is a projected “fork” of the generously given ways of make use by the developers of Delta Chat-App. Although still required to “just” make use of the common app, the manual here contains already additional features starting by new “brand” “Sārahārī-Saṅghaṁ” (Pali language, meaning “the Sangha's/community of monk's admirable messenger” or “admirable messenger for the Sangha”), replacing the common “Delta Chat” name. The manual is meant to be of good and easy use for foremost non-IT-specialist, normal user. The section FAQ has been adopted but might include spheres not so accessible, especially for monks (third part tools…). All else should be seen as consciously given and free of strings binding back to world but dedicated and heading toward beyond.
May everybody feel welcome if inspired to give into the App-development an/or the manual here. Translations into other languages are more then welcome as well.
Once uploaded app and set an account, one is given to maybe start to join via scanning one of those QR-codes here, as starter:
A topic on the origin of this manual can be found at Delta Chat's support forum: “Comprehensive Manual for DC” and at sangham's forum. One should feel always welcome to expand the manual and/or contribute corrections if feeling inspired.
development repositories and also Delta.chat discussions in general
Given download for the Sārahārī-Saṅghaṁ can be found here: Sangha-messanger app - សារហារីសង្ឃ (android) (offical version and one of the last developer-version, incl. Khmer)
One can as well given download the Delta-Chat software for serial platforms.
If up to install a new version it's recommended to first make a backup of your existing data and settings.
Use “Log in to your server” to setup your account by using your own email. (This option is also used for additional accounts later, under switch account in the main menu available) There is no use of any third-part server, registration, and no connection to resources other then your own email-account.
If not having an email account, may one feel given to ask for a personal “
…@sangham.net”-email-account for what ever harmless and non-commercial good undertakings here or send a SMS “
need email for *your name*” to
Delta-Chat has an informative list of email-provider, useful for common purposes.
Usually simply enter your email address and your server-password (it will not be shared and stays at your device only) is enough for the setup. It works very well using
sangham.net-email, and no ajustments are required. The auto-progress might require some time.
Certain provider require to get into the advanced SMTP settings:
After having chosen this action hold the device camera above the image. It will recognize it by itself.
When one sets up an additional device to use Delta-Chat in synchronized way, or if a new Installation is undertaken, or if installing other versions, like Delta-Chat Dev, this way will import you previous Backup. Be sure, if it is not found automatically, that the backup is found in the device's download-folder.
If there are more backups, the software will select the latest. If you import backups for more the one account (each account currently requires separate backup) it's required to delete the already installed. Otherwise it would always the last. Details on it see backup, available in the main menu under settings » chats and media to be executed.
Most settings and options are found in the two menus:
Additional menus are:
Following the single functions in detail:
By choosing this option a list, containing all (detail?) contacts appear. By clicking a certain contact wished messaging can be started.
In cases where a contact does not exist now, best to use the upper line for search to write a new email inside and then push the
+ next “New contact”.
More in regard of storage and origin of addresses see address-list
Clicking “contact requests” in the main menu, messages which are related to a certain chat, single or group, would be displayed on a new page opened. Whether new contact request would be displayed or not depend also on the settings in chats and media, whether “all” is set in Show classic email or not.
Accepting to “chat” with a new contact opens an new chat and it's not necessary to response in this chat to have it then listen in your chat-list. For Maillist no replay to the sender is possible but most other actions with messages found in the action-menu once accepted.
Contact requests are usually also shown at the beginning of your chat-list and can be accessed there as well, yet one by one directly.
Following main chapters are found here:
Once you have finished to edit your profil setting, click the ✅ in the right upper corner to return done with your action.
Chosen name will be displayed on receiver side in addition to ones email address and possible saved in others address-lists.
By default “
Sent with Sārahārī-Saṅghaṁ Messenger, please download it as well here: https://forum.sangham.net/index.php?action=tpmod;dl=item757 or via https://delta.chat ” will be attached after the text in one's send email. One is given to edit it as wished.
By touching the default auto-avatar (colored circle with initial character) one can chose another by serial (and variable) devices possibilities, using one of the suggested. The avatar will be send as attachment with every email and possible get stored on receiver side. Naturally such can not be made undone for already send messages.
Allowed file-formats: jpg, png,…(?)
No, chats only
Only accepted contacts
others emails would not appear on the app.
Tips & Tricks:
… or unblock
Here one can find previous blocked contacts set via the action block contact in the contact menu, and also make the unblocked. By clicking on one contact listed, one can chose to “unblock contact” it. It will then appear again in the chat-list.
Enabled one allows to give info-email back on request whether others incoming messages had been received or not. This email reports status to be seen under info-action used for a message. By default this option is enabled.
Note: If this is disable one wouldn't receive an info about other, and not only not giving info on request.
By default this option is disabled to allow usual line break by the use of enter key. Some may like to use the enter key for the action “send” instead of clicking it's icon. In this case it needs to be enabled.
(Alternative key-combination for line break when enabled?)
To save traffic and server space, maybe not only to save money but remembering the heat it causes globally, one can select different kinds of media quality for the attachments.
You can chose between:
Here one can set time periods after which ones send and received messages would be deleted from ones own store. If searching for ways to common agree of deleting messages (means also on others devices and/or server, try out the “disappearing messages-option” in the particular chat-menu
To create a backup for possible import of backup-action, one can use this option found in the settings under “Chats and media”. It will save all messages, contacts, important setting and you end-to-end Autocrypt setup in a zip-file on you device in the download folder like “”
delta-chat-backup-2021-02-20-00.tar“”. The last two numbers may go up to
02… if there are more then one backup made. Important! Delta-chat does not make only one backup for all your accounts but it's required to make a backup on each account separately. Good to remember which account's backup was made first to know which is for which account.
One may use a backup for:
Under this category in the settings one is able to customize one's preferred way becoming notified.
Following options are found here:
Be sure that notifications are enabled in general advice settings if wishing to use them.
Here one can turn notifications generally on and off. By default “on” is set.
This requires to turn on notifications and ensures connection best as possible. See also: killing apps and battery use. Once enabled the Sārahārī-Saṅghaṁ logo in the notification area is shown gray permanently.
Activates the LED notification (in addition) if the device allows such. From various colors can be selected ones preferred.
An option to chose which information will be displayed when notified.
…can be activated
Here you can order different effort to win over other processes in regard of your Delta-Chat notifications on your device.
Select sound to be heard for incoming messages when particular chat is opened or app else active used.
In this setting one can disable it's use.
Enable this option to avoid best that screenshots of messages and lists are made.(?)
This option enabled hinders possible set auto-learning of keyboard while typing be disabled to avoid cache of text passages or words elsewhere on you device.(?)
End-to-end encryption allows “secret” communication between two devices directly. This means encoding/decryption happens only on ones and the other device and nowhere else. This requires the sending and receiving of a key which is usually made automatical with the fist email contact but can also made in manual ways of exchange with the import backup and backup tasks…(?)
To get informed when email arrive in your email server inbox which are not from recognized contacts or chats yet (would possible not automatical moved in Sārahārī-Saṅghaṁ folder). Emails may then appear in contact requests) (?)
Likewise above for sent folder server-side. (?)
Likewise above for Sārahārī-Saṅghaṁ folder server-side. (?)
Enable to save a copy of outgoing messages as email on your server in the “deltachat” folder. Useful if wishing to access them also when using multiple devices or to have a backup for cases datas on the device or device get's lost.
Tip: Surely good to think generally where one likes to store mainly if wishing to manage order and less memory-usage, on device or on ones server. Maybe consider to enable timely deleting of messages on temporary store. See settings: Delete old messages.
Using together with the options given under map one may allow to access to one's location.
If required to know what has been going on behind the screen: Here a log where infos are stored.
In advanced settings menu the same target is reached by clicking it. Under it, in the setting menu, one finds the version of ones app. Useful to share when asking for help in the Support forum (https://support.delta.chat).
How ever… it directs one to the offline FAQ-list and maybe something like this here in times to come.
Generally: May one always feel invited to ask for help or to raise issues in the online-monastery forum.sangham.net, or via email, or chat directly, addressing email@example.com or firstname.lastname@example.org. No special formalism required at all.
On each chat or conversation page a menu is found at the right uper corner containing following options:
…and are discussed in detail below.
This function, found in the chat-menu, allows one to search text-strings within a chat and highlights messages containing the string for a short while. In cases where the string is found in a quoted part of a message colored highlighting wouldn't appear (a bug?).
Another feature in all recent Delta Chat versions on all platforms, and the Sārahārī-Saṅghaṁ, are the so called “Disappearing messages”, similar to the Signal-messenger offering. This function, a group- or chat-setting, change-able by all group-members, can be selected in the particular chat's menu, can be set separately for each chat.
Once the feature is enabled in the settings, any user can decide to see all subsequent messages disappearing.
After a chosen timeout, the later send messages of this chat will disappear on all the users devices, on the users server - and moreover, also on devices and servers of the other group members, if they are using and the Sārahārī-Saṅghaṁ or Delta Chat. So when nobody made any copy, backup, screenshot or forwarded such kind of messages elsewhere, they disappeared.
Note: The Delta-Chat app must be active and connected with the Internet to execute the deletion timely. If this isn't the case, deletion on each user's side of the group, would be done only as soon the app would be active and connected again.
Note: Like all ways of outwardly protections are fragile, this option is no guarantee that no copies, forward, screenshots… had been made of thought being disappearing messages. So good to stay secure by ones conducts in not harming anyway. Done can never be made undone.
Dev: This action sets
Ephemeral-Timer: *time in seconds* in the header of messages.
Corresponding codes: link?
It's possible to add attachments, files, to ones message. One can either chose this possibility available next to the message-editor - writing afterwards a message optional to it - or, if one has started to write, select the option in the chat-menu. The attachments previously shared in a chart can be viewed and/or searched in a list in on the chat-options page. There are many ways to select a source, also depending on ones device and settings.
On clicking this option in the chat-menu, an info whether sure about it will be appear, since you can not join again easy by your self unless another would invite you, or you still have the invitation OR code:
Once pressed “yes” a message about the leave would be send to all and also appear on you chats-display:
Although you still can open the chat, you would no more receive new messages from it as well not able to write in this group. So maybe you like to consider to simply mute notifications from it, if currently stressed by messages from it.
… or archive
One has the possibility to select “Archive Chat” in the Chat-menu. This action would put this chat in the background of the chat-list and no more appear on it, only found at the end of it in the archived chats-folder.
… or archived
Are found at the end, on the buttom, of your chat-list, mentioning their amout as well.
… or unarchive
Once chosen this opinion the delete a chat, since it could not be made undone easily, one would get an information that this action causes the messages and chat-infos to be deleted on ones device (not on the server), and asked whether progress or not:
Here one can add or edit the group's name and by clicking on the Avatar select a picture found on the device. After selecting the file one is leaded to a simple avatar-editor. Here one can size and crop the image and accept it by clicking “Done” in the right upper corner.
The profil page can be also reached by clicking the avatar in the chat-header instead.
That option can be also reached via the chat-menu. If you feel to much disturbed by a chat's messages, instead of thinking to leave a group (since not easy to join again without a member adding you), one has the possibility to mute chats. No notifications would be arising for chosen time.
An icon would appear in the profil-header and in the chat-list as well. This settings can be changed and unmute made in the chat-menu as well. Nobody would be informed and possible stressed about this “leave” for a while.
… or unmute
One can select a custom sound for each contact-profil- or chat-profil. This option will open to your possibilities to reach storages on your device for selecting a wished file. Supported audio-files are mp3,…(?). See also sound in the general settings.
Option to vibrate turned on or off like set in the general settings.
A participate contact might currently run:
The profil of the single contacts contains similar menu as View profil for chats, except the options for setting notifications, as sound and vibrate settings if this contact does not use Sārahārī-Saṅghaṁ, but can be set within single chats. See for more: View profile.
In addition it maintains the action
It's currently not possible to set a contact-avatar manual, and depends on whether the contact has added a picture by himself or not. By default colored circles with initial character of the contact name are displayed if sender hasn't set a personal avatar.
Allows to change the displayed Name (usually email address if non is set) of certain contact in the contact profil but also in the chat-profil in combination with setting an avatar, and called “Group image and name”
To mark a message, for certain action, as selected, touch the area of it's row a little longer till marked blue (best outside the message's frame). Then icons for action appear instead of the chat-header.
Once one message is marked this menu for message actions will be displayed (incl attachment is selected:
Once more then one message is marked this menu for message actions will be displayed:
Note: Quoting can also be made by wiping a message to the right.
Note:_ Delete can not made undone.
Use this action to save a picture, voice-message or document/file attached to a selected message.
A message can be forwarded to another chat. Once clicked you can chose in which chat or charts to share, back in the chat-list, by select the wished. Is also way to save messages in the folder “saved messages”
This is found as selection under the three dots and used to answer direct to the message sender in a new chat
Main collection of Download and info on public download: https://delta.chat/de/download
Source Code can be found here.
Minimal requirements: Android 4.1
A given Android version, dedicated toward the Sangha and it's follower, can be downloaded here: https://forum.sangham.net/index.php?action=tpmod;dl=item757
Source Code can be found here.
Homebrew manual install:
brew install –cask deltachat
Minimal requirements: macOS 10.10 Yosemite
Minimal requirements: Windows 7
Flatpak manual install:
flatpak install flathub chat.delta.desktop
Arch manual install:
yay -S deltachat-desktop-git
Source Code can be found here.
Minimal requirements: Ubuntu 12.04, Fedora 21 or Debian 8 or compatible systems
Here one can find the last version from the eager working Developers: https://download.delta.chat/android/nightly/
Discussion and info on Use of nightly-versions android
For Android, you can verify the signing certificate on the APK matches one of the following SHA256 fingerprints:
For F-Droid downloads:
Other APK downloads:
To print the SHA256 fingerprints of the APK signing certificate you can use eg.
keytool -list -printcert -jarfile <APK-file>
This section contains defined expressions not found under certain menu option and explains them.
An account for the use of Sārahārī-Saṅghaṁ requires an own email account which is used for store your messages as usual email. No register on any third part server required.
One can uses multiple accounts (email accounts), each separate, to easy communicate.
If you delete one or more accounts on the Delta-chat app wouldn't effect your data on your email-server.
For help or advice to gain an email-account good useable with the app see email.
DeltaChat (android and iOS) reads contacts from the system address-book (Q: of the device?) when the user allowed (Q: where? app-access?) it to access that list.
Info: Currently there is no option to import into, or export from the app's address-list.3)
Messages allow also to add attachment(s). The maximum size for such files to be send is 49.1 Mb (?). Received attachments can be saved separately (by downloading them to ones device) and collected viewed in either the chat-gallery or the list of chat-docs of a particular chat.
“Contact” denotes a conversation partner via a certain email stored in the app's address book. A list of available contacts as well as the possibility to add a new contact is given within the option new chat. See also address-list for further infos.
Denotes either a group conversation or a conversation between two people. A chat is technical a selection of emails under one certain topic. See also details under menu option New Chat.
The colored block on the top of the screen is here denoted as “Chat-header” and displays the chat-name, possible a clock-image showing that the option disappearing messages for this chat is activated, as well the number of the current group-members and the group-image.
Under the options the group member list is found.
The list of a chat's file-documents, previously shared by it's group-members, can be accessed via the page for chat-options. It contains all (?) files shared as attachment excluding shared pictures, which are found in the chat-gallery.
The list of a chat's images, previously shared by it's group-members, can be accessed via the page for chat-options. It contains all (?) images shared as attachment. Other shared attachments are found in chat-doc.
Is a folder found in the chat-list and contains default by installation or update of the version an info-“message” about new features.
As the folder actually just reports device-side infos, they aren't send by anybody else then the app-software on your device. Notifications about problems with login to your email-account, for example, may be stressed out here. One can of course not replay to those infos-messages as it is actually not a normal chat.
… or email-account:
The apps use is based on using your own available server, your email-server(s). Register an account does not require a new but using what one might already have or gain newly where ever wishing to store ones communication Data.
For which providers work well with Delta Chat, in general, an informative list of email providers is available.
When register an account for using the app on certain email address one gives the app the possibility to connect one to own email server but wouldn't share all with anybody or elsewhere at all. All stays either on your device or on your server.
Denotes the email address of a certain contact, or one of your used email addresses for each of your account. An/your email address as well as the password to your email-server is required to setup a new account. Contacts, if no custom name has been set in ”edit name, are displayed by their email address in the chat-list as well as in the contact-list.
If one does not have an email account or likes to know which provider serves good conditions for Sārahārī-Saṅghaṁ's use, here an informative list by the App-developers: Provider Overview. The list contains also hints and tips for supportive settings.
The Venerable members of the Sangha and it's faithful followers are given to request a donated email account and are given to do so via the online monastery sangham.net or via SMS, sending “need email account for *
your Name*” to +855 12345025. Access-dates would be likewise send.
Select New chat and then
(+) New group from the menu in the upper right corner or hit the corresponding button on Android/iOS.
On the following screen, select the group members and define a group name. You can also select a group avatar. As soon as you write the first message in the group, all members are informed about the new group and can answer in the group (Note! As long as you do not write a message in the group the group is invisible to the members).
Every group member has the same rights as any other. For this reason every one can delete every member or add new ones.
…or Group member/Group-members:
Are selected members of a group or chat. They can be added or removed by any member of the group. Messages shared within a chat are delivered to all members of it. Thought it's always possible to answer on a message privately. There is no such as an admin within every chat and all share the same possibilities. Group members need to be always invited, added by someone within particular Chat. See “Add members to a group” and “view profil” in the Chat-menu.
The inbuilt text-editor allows one to direct contribute to a chat.
On the left, next to the text-field, one finds the option to select emoji, if use is enabled in advanced-setting. One can also add attachment of files, clicking the green icon, record a voice-message by pushing the microphone-image, or take direct a picture to be attached, using the camera-sign.
A small circle tells one that the message is still pending and didn't leave the outbox, or not to all all recipients could be reached proper. Clicking “info” in the action-menu may lead to more details or look into error mail delivered in your email inbox on it.
There are three kinds of profil-pages, yet the general function and layout is similar:
One can scan OR code to access a particular chat via a given OR image. Within the chat-profile, reachable via ”view-profil“ in the chat-menu the corresponding OR for a chat can be found and shared letting others join the group.
One can use the OR here to join the chat “Comprehensive Manual Sārahārī-Saṅghaṁ” - if still existing - by pressing the image and chose “share”, whereas Sārahārī-Saṅghaṁ should open. (?)
Topic in the support forum: [Manual] OR code (tips and tricks), and bugs?
This folder, visible in the chat-list contains separate saved messages. With the option forward in the action-menu messages can be brought here by selecting this folder. This possibility gives ways to:
Although the text-editor is available, the send-button here serves just to save a massage with this ”chat“-like folder. Of course one can send by forward out of this box, or use the “chat” for talks with oneself herein.
When spoken about “server” here no central or any large companies server is meant but your own email-server. There is not server storing anything maintained by the app developers and one stays free to chose where one's communications are stored beside of one's device. Access to your server is needed for setup an account to make use of the email-messenger. See some detail under email provider in cases not having an email account yet.
To access you emai-account, if being given one on the sangham.net-server, use the web-interface:
To login use your email-address and given password. There you can find all stored messages, set settings, edit password, and use email as usual from everywhere.
It's more then comfortable to record voice as a alternative contribution to a chat, using the camera-sign next the message-editor. As long the sign stays touched on, recording endures. Once released the record would be saved and also send right after. Voice messages can be shared and stored like other attachments easily.
Files are produced and saved in aac-file format and those voice-messages can be separately saved by marking in in the chat and select the save-option appearing in the chat-header. Listen: 2021-02-21-08-11.aac
Frequently Asked Questions
… or ”Delta Chat“, or ”What is What is Delta Chat?“.
Specifically for the Sārahārī-Saṅghaṁ please see ”general“.
With Delta Chat, you can write to every existing e-mail address - even if the recipient is not using the Delta Chat app. No need for the recipient to install the same app as yours, as with other messengers.
Your data is not saved on a central server unless all users are using the same e-mail servers.
Largest userbase - recipients not using Delta Chat can be reached as well.
Elegant and simple user interface. Distributed system.
No Spam - only messages of known users are shown by default.
Delta Chat automatically shows:
Messages in common spam folders are ignored and contained addresses are not considered as known contacts. As messages from unknown contacts do not pop up automatically, normally, there is no spam.
However, if needed, you can block any contact.
Yes. Beside the plain text, all e-mail attachments are displayed as separate messages. Outgoing messages get attachments as needed automatically.
Contacts who don’t use Delta Chat see it as an E-Mail attachment.
For privacy reasons, no one sees your profile picture until you write a message to them.
Your profile picture isn't sent with every message, but regularly enough that your contacts will re-receive your profile picture, even if they add a new device.
Yes. If an incoming e-mail lacks a plain text part, HTML-emails are converted to plain text in the app. Outgoing e-mails always use plain text.
As with other E-Mail programs like Thunderbird, K9-Mail, or Outlook, the program needs the password so you can use it to send mails (see setup). Of course, the password is stored only on your device. The password is only transmitted to your E-Mail provider (when you login), which has access to your mails anyway.
If you use an E-Mail provider with OAuth2 support like gmail.com or yandex.ru, there is no need to store your password on the device. In this case, only an access token is used.
As Delta Chat is Open Source, you can check the Source Code if you want to verify that your credentials are handled securely. We are happy about feedback which makes the app more secure for all of our users.
Depending on the operating system in use, you may be asked to grant permissions to the app. This is what Delta Chat does with these permissions:
take pictures and videos: for sending
read your contacts: to discover
contacts to chat with
access approximate location (network location sources): for the location streaming feature
access precise location (GPS and network location sources): for the location streaming feature
record audio: for audio messages
modify or delete the contents of your SD card: to download message
read the contents of your SD card: to share files with your contacts
run at startup: so you don’t have to start Delta Chat manually
control vibration: for notifications
view network connections: to connect to your E-Mail provider
prevent phone from sleeping: so you can easier copy the security code during the Autocrypt Setup Message
have full network access: to connect to your E-Mail provider
view Wi-Fi connections: to connect to your E-Mail provider
As soon as you write the first message in the group, all members are informed about the new group and can answer in the group (as long as you do not write a message in the group the group is invisible to the members).
Every group member has the same rights as any other. For this reason every one can delete every member or add new ones.
To add or delete members, click on the group name in the chat.
A verified group is a chat that guarantees safety against an active attacker. All Messages in a verified chat view are e2e-encrypted, and members can join by scanning a “QR invite code”. All members are thus connected with each other through a chain of invites, which guarantee cryptographic consistency against active network or provider attacks. See countermitm.readthedocs.io for the R&D behind this feature.
As of Dec 2019, a “verified group” remains an experimental feature. It is continuously improved and many bugs have been fixed since the original introduction in 2018. However, there remain cases, especially with large groups where inconsistencies can occur, or messages become unreadable. Early 2020 a security review is upcoming, and several new developments around qr-join protocols are taking place so chances are we remove the “experimental” label not too far in the future.
As you’re no longer a group member, you cannot add yourself again. However, no problem, just ask any other group member in a normal chat to re-add you.
As an alternative, you can also “Mute]d” a group - doing so means you get all messages and can still write, but are no longer notified of any [[#new messages.
A message shows double ticks after more than half of the recipients have seen the message on their display. Note that some recipients might have disabled read-receipts for privacy-reasons.
If more than 50% in a group disabled read receipts, the double ticks will never show up. For more detailed information, see this blogpost.
Yes. Delta Chat implements the Autocrypt Level 1 standard and can thus E2E-encrypt messages with other Autocrypt-capable apps.
Delta Chat apps (and other Autocrypt-compatible e-mail apps) share the keys required for end-to-end-encryption automatically as the first messages are sent. After this, all subsequent messages are encrypted end-to-end automatically. If one of the chat partners uses a non-Autocrypt e-mail app, subsequent messages are not encrypted until an Autocrypt-compliant app is available again.
With most mail servers, Delta Chat establishes transport encryption (TLS). This only secures the connection between your device and your e-mail server. Whereas e2e-encryption provides safety between your device and a friend’s device.
If you are within immediate distance of the chat partner:
Select QR Invite code on one device and then Scan QR code on the other one and scan the code. If both devices are online, they will introduce a chat channel with each-other (if it doesn't exist already) and the encryption keys will also be verified. Both will see a “sender verified” system message in their 1:1 chat.
For transport encryption, this state is just shown there
A little padlock shown beside a message denotes whether the message is end-to-end-encrypted from from the given sender.
If there is no padlock, the message is usually transported unencrypted e.g. because you or the sender have turned off end-to-end encryption, or the sender uses an app without support for end-to-end-encryption.
Autocrypt is used for establishing e2e-encryption with other Delta Chat and other Autocrypt-capable mail apps. Autocrypt uses a limited subset of OpenPGP functionality.
Delta Chat implements countermitm setup-contact and verified-group protocols to achieve protection against active network attacks. This goes beyond the opportunistic base protection of Autocrypt Level 1, while maintaining its ease of use.
1:1 chats with a verified contact and verified groups are not the same, even if there are only 2 people in the verified group. One difference is that you could easily add more people to the group, but there are other implications as well.
Verified groups are invariably secured. Any breakage (cleartext or wrongly signed messages etc.) will be flagged and such messages will not be shown in this chat. You can trust all messages in this verified-checkmark chat to have not been read/altered by middle parties.
1:1 chats are opportunistic, it is meant to allow people to communicate no matter if they change e-mail clients, devices, setups etc. That’s why there is no verification checkmark, even if you have verified the contact.
No, OpenPGP doesn’t support Perfect Forward Secrecy. Perfect Forward Secrecy works session-oriented, but E-Mail is asynchronous by nature and often used from multiple devices independently. This means that if your Delta Chat private key is leaked, and someone has a record of all your in-transit messages, they will be able to read them.
Note that if anyone has seized or hacked your running phone, they will typically be able to read all messages, no matter if Perfect Forward Secrecy is in place or not. Having access to a single device from a member of a group, will typically expose a lot of the social graph. Using e-mail addresses that are not easily tracked back to persons helps group members to stay safer from the effects of device seizure.
We are sketching ways to protect communications better against the event of device seizure.
As Delta Chat is a decentralized messenger, the metadata of Delta Chat users are not stored on a single central server. However, they are stored on the mail servers of the sender and the recipient of a message.
Each mail server currently knows about who sent and who received a message by inspecting the unencrypted To/Cc headers and thus determine which e-mail addresses are part of a group. Delta Chat itself could avoid unencrypted To/Cc headers quite and always put them only into the encrypted section. See Avoid sending To/CC headers for verified groups. For opportunistic chats the main concern is how it affects other mail apps who might participate in chats.
Many other e-mail headers, in particular the “Subject” header, are end-to-end-encryption protected, see also this upcoming IETF RFC.
Yes. The best way is to send an Autocrypt Setup Message from the other e-mail client. Look for something like Start Autocrypt Setup Transfer in the settings of the other client and follow the instructions shown there.
Alternatively, you can import the key manually in “Settings” or “Advanced settings” and then “Import secret keys”. Caution: Make sure the key is not protected by a password, or remove the password beforehand.
If you don’t have a key or don’t even know you would need one - don’t worry: Delta Chat generates keys as needed, you don’t have to hit a button for it.
The most likely cause is that your key is encrypted and/or uses a password. Such keys are not supported by Delta Chat. You could remove the passphrase encryption and the password and try the import again. If you want to keep your passphrase you’ll have to create an e-mail alias for use with Delta Chat such that Delta Chat’s key is tied to this e-mail alias.
Delta Chat supports common OpenPGP private key formats, however, it is unlikely that private keys from all sources will be fully supported. This is not the main goal of Delta Chat. In fact, the majority of new users will not have any key prior to using Delta Chat. We do, however, try to support private keys from as many sources as possible.
Removing the password from the private key will depend on the software you use to manage your PGP keys. With Enigmail, you can set your password to an empty value in the Key Management window. With GnuPG you can set it via the command line. For other programs, you should be able to find a solution online.
Delta Chat uses the Autocrypt e2e-encryption standard. For a discussion of Autocrypt and pEp, see the Autocrypt FAQ.
If you want to use the same account on different devices, you should export a backup from the old device, and import it into the new device:
On the old device, go to “Settings” or “Settings / Chats and media” and then to “Backup”. Enter your screen unlock PIN, pattern, or password. Then you can click on “Start Backup”. This saves the backup file to your device. Now you have to transfer it to the other device somehow.
On the new device, on the login screen, instead of logging into your email account, choose “Import Backup”. After import, your conversations, encryption keys, and media should be copied to the new device.
You are now synchronized, and can use both devices for sending and receiving E2E-encrypted messages with your communication partners.
There are no immediate plans but some preliminary thoughts.
There are 2-3 avenues for introducing a Delta Chat Web Client, but all are significant work. For now, we focus on getting stable releases into all app stores (Google Play/iOS/Windows/macOS/Linux repositories) as native apps.
If you need a Web Client, because you are not allowed to install software on the computer you work with, you can use the portable Windows Desktop Client, or the AppImage for Linux. You can find them on get.delta.chat.
This is an experimental setting for some people who are experimenting with server-side rules. Not all providers support this, but with some you can move all mails with a “Chat-Version” header to the DeltaChat folder. Normally, this would be done by the Delta Chat app.
Watching the Inbox makes sense to turn off, if you have both:
In this case, Delta Chat doesn’t need to watch the Inbox.
Sending a copy of your messages to yourself ensures that you receive your own messages on all devices. If you have multiple devices and don’t turn it on, you see only the messages from other people, and the messages you send from the current device.
The copy is sent to the Inbox, and then moved to the DeltaChat folder; it’s not put into the “Sent” folder. Delta Chat never uploads anything to the Sent folder because this would mean uploading a message twice (once through SMTP, and once through IMAP to Sent folder).
The default setting for copy-to-self is “no”.
The only reason one wants to watch the Sent folder is if you are using another mail program (like Thunderbird) next to your Delta Chat app, and want your MUA to participate in chat conversations.
However, we recommend using the Delta Chat Desktop Client; you can download it on get.delta.chat. The option to watch the “Sent” folder might go away in the future. It was introduced at a time where there was no Delta Chat Desktop client available on all platforms.
Some people use Delta Chat as a regular email client, and want to use the Inbox folder for their mail, instead of the DeltaChat folder. If you disable “Watch DeltaChat folder”, you should also disable “move chat messages to DeltaChat”. Otherwise, deleting messages or multi-device setups might not work properly.
With a rather good chance: Yes :) However, some providers need special options to work properly, see Provider Overview
Sending and receiving messages takes a few seconds, typically. Sometimes there are cases where it takes longer but that is arguably true as well for any other messenger.
Instant chatting works fast if both parties are actively using the app. It’s sometimes slower if the app is running in the background.
Receiving messages then can take minutes because both Android and iOS often stop Delta Chat from running in the background, and only wake it up occasionally. This artificial delay is usually worse on iOS than on Android. Note that Delta Chat doesn’t use Google Cloud Messaging (GCM) or the Apple Push Notification Service (APNS), because this leads to user tracking and central control which Delta Chat aims to avoid as much as feasible.
However, Android and iOS kill apps running in the background is a problem for many legitimate apps. For more information, see dontkillmyapp.com.
Yes and No.
No, you can not use your Protonmail, Tutanota, or Criptext account with Delta Chat; they do not offer receiving mails via IMAP.
In any case you can use Delta Chat to send Messages to people who use Protonmail, Tutanota, or Criptext. Those messages will not be End-to-End encrypted, though. The End-to-End encryption those providers offer is only working inside their platforms, and not compatible with anyone outside.
Delta Chat can e2e-encrypt through any e-mail provider with any Autocrypt-enabled e-mail app.
See Standards used in Delta Chat.
First of all, Delta Chat does not receive any Venture Capital and is not indebted, and under no pressure to produce huge profits, or to sell users and their friends and family to advertisers (or worse).
Delta Chat developments have so far been funded from four major sources:
The monetary funding mentioned above was organized by merlinux GmbH in Freiburg (Germany), and then distributed to almost a dozen contributors.
Funding for 2020/2021 is yet to be determined. We are pursuing several opportunities with different organizations and partners. We also are considering to ask for donations. In fact, we experimentally started a little Delta Chat / Liberapay donation account but have not published this yet. There were also around 3-4K so far donated to Bjoern’s (the original author of Delta Chat) paypal and bitcoin donation channels.