Page tree
Skip to end of metadata
Go to start of metadata

WARNING: The messenger is still in an early stage of development and therefore may have errors. Please report any bugs to the support service.

The university messenger can be used for communication between students, professors and staff and provides the following features:

  • Message exchange from messenger to messenger
  • Message exchange from e-mail to messenger
  • Message exchange from messenger to e-mail
  • Sending of media and location

DeltaChat offers many advantages in contrast to WhatsApp and other messaging platforms (see below).


User Guide

Installation on your smart phone

Download the application using the QR Codes and the relevant official App-Shop:


            Android                               IOS - Apple

You can download the desktop client for Windows, Linux and Mac from the official website:

  • If you want to use the desktop application at the same time as the mobile app, please refer to the section "Using desktop and mobile clients at the same time: synchronising clients".
  • If you are using windows, please refer to "installation using Windows".

After installing the clients, you can use your university e-mail and password to log in (advanced settings are not required).

Installation using Windows

When using Windows, it is important to note that the current version has not yet been tested and certified by Microsoft. Therefore, the following warning must be accepted during installation:

This step will be dropped in future versions.

Using desktop and mobile clients at the same time: synchronising clients

Since messages in DeltaChat are encrypted end-to-end (see FAQs), all DeltaChat applications using the same e-mail address must have the same key.

Send Autocrypt Setup Message

After installing and logging in on both devices, go to Settings → Advanced and click "Send Autocrypt Setup Message". Now you can send and receive on both devices.

Alternative possibility to exchange keys

If the "Autocrypt setup message" does not work for some reason, this can achieved using the backup function.

Proceed as follows:

  1. Create a backup on A (see "Creating and importing a backup" → "How to create a backup").
  2. Import the created backup to B (see "Creating and importing a backup" → "How to import a backup").

You should now be able to receive and send all messages on both clients at the same time.

Using a new device

To copy the message history and key from an old device (A) to a new device (B), complete the following steps:

  1. Create a backup on A (see "Creating and importing a backup" → "How to create a backup").
  2. Import the created backup to B (see "Creating and importing a backup" → "How to import a backup").

Creating and importing a backup

All messages and keys are included in a backup. Therefore, the backup is suitable for backing up data as well as moving or synchronising clients.

How to create a backup

To create a backup in DeltaChat, you must be logged into DeltaChat on the device.

  1. In the DeltaChat main window, click (three point menu) → Settings →  Chats and Media →  Backup
  2. Follow the instructions until the data is backed up
  3. Copy the created backup to a safe place or to another device.
    • Transfer the backup wirelessly or using a USB cable.
    • Note: On Android, the backup is usually located under "Internal Storage → Downloads".
    • With iOS, you can use Airdrop.

How to import a backup

  1. Install DeltaChat on the device (do not log in)
    • If you are already logged in, reinstall the app on your mobile device or (in the desktop client) click (three point menu) and click "Switch account". You should now have returned to the login screen.
  2. Copy the backup file to the device
    • Transfer the backup wirelessly or using a USB cable.
    • Note: On Android, the backup is usually located under "Internal Storage → Downloads".
    • With iOS, you can use Airdrop.
  3. On the DeltaChat login screen, select "Import backup"
  4. Select the transferred backup file and start the import process
  5. In the app, you will be automatically logged in. In the desktop client, a new profile will appear, which you can then use.

Using DeltaChat as primary e-mail client

Note: this option is usually only required if you do not want to otherwise use an e-mail client (Outlook).

By default, DeltaChat only shows chat messages which were sent by other DeltaChat clients. If you want to display all e-mails in DeltaChat, you need to adjust the following options in your (mobile and desktop) client:

  1.  (three point menu)  →  Settings →  Show normal e-mails →  All

Tipps for using DeltaChat 

Collected tips from feedback and experience -


  1. Easy direct contact via QR code: to make direct contact quickly and without entering an e-mail, you can display your own QR invitation code on the main screen of DeltaChat ((three point menu) → QR invitation code). This can be scanned by another DeltaChat user (in the main DeltaChat screen, click the QR code symbol in the top right) to start a chat
    1. If you have a public address, you can print out and hang up the QR code, making it very easy for others to contact with you.

Tips for groups

  1. Mixed groups: In groups of more than three, all participants should use DeltaChat. In messengers, often short messages are exchanged and this can result in the members who don't use DeltaChat receiving many emails with one word or smilies without much context.
  2. Adding members: For the best user experience, only add people to groups if they already use DeltaChat and have sent you a direct message there, otherwise confusion may occur (see "Why don't I see existing chats after reinstalling?" below). 
  3. Group QR code: You can also invite people to a group using a QR code. To display the QR code, go to the group profile and select "+ QR invitation code" under "Add member". Others with DeltaChat can then use the QR scanner (under the QR code symbol in the top right) to scan the code and automatically enter the group. This has the following advantages:
    1. You do not need to enter e-mail addresses
    2. You can ensure that the person is already using DeltaChat (see points 1 & 2 above)
    3. Many people can join the group at the same time without you having to invite everyone individually (e.g. in a lecture)
    4. You can offer public groups by printing and hanging up the QR code.



 How does DeltaChat work?

ALL messages are packed and sent by DeltaChat as an e-mail. This includes text messages, messages with media content and also status messages such as the "read ticks".

 What is DeltaChat's position regarding data protection or GDPR?

Since DeltaChat only communicates via e-mail and does not send any data externally, DeltaChat fully conforms to the GDPR. 

 Which advantages does DeltaChat have compared to other messengers?
  1. You do not have to pass your phone number on to any third parties (your university e-mail is already known)
  2. You can reach anyone who has an e-mail address, even if they do not use DeltaChat (this person will receive a normal e-mail).
  3. You do not transfer your address book to third parties (GDPR compliant).
  4. Secure data exchange through end-to-end-encryption.
  5. No transfer of metadata, as the mail server is operated by the Computer Centre of Reutlingen University.
  6. Possible integration into existing processes at the university → coming soon.
  7. Further technical advantages can be found in the official FAQs of the DeltaChat developer:
 Is DeltaChat dangerous (privacy / spam)?

In certain reports (e.g., DeltaChat has been criticised for various aspects. Here are some responses:

"Problem" according to the article:

  1. All e-mail addresses of group members were plainly visible
    • Same problem with e-mail: if I send an e-mail to a lot of  people and put someone else in the "To..." or "CC...", everyone else will see the new e-mail address. 
    • When using WhatsApp etc. it is even worse as the phone number is distributed.
  2. ... to organise his newsletter distribution more easily using a DeltaChat group...
    • In DeltaChat you can also work with mailing lists so that not everybody can see all addresses. For this, a mailing list address has to exist and not a normal group.
    • DeltaChat is not intended for this purpose. One would not normally use a WhatsApp group to send a newsletter, so the idea is strange.
  3. Something similar to the bcc function for e-mails is missing in DeltaChat groups
    • This is correct, but the service is intended as a messenger, where no such function exists or would be necessary. 
    • DeltaChat is not intended to replace the "normal" formal e-mail. For functions such as bcc, please look Outlook or similar options.
  4. In addition, the e-mails lacked the legally required opt-out option for group mailings
    • This is not a DeltaChat problem alone: spam mail without the unsubscribe option have existed since e-mails have e-mails. In Outlook unwanted mails can also be sent and received - this has little to do with DeltaChat.
    • When I am using DeltaChat, I get only DeltaChat messages by default, which means I receive no spam mail. If I do receive unwanted notifications, I can simply "mute" these contacts or groups to prevent them from being displayed.

Conclusion: DeltaChat is based on e-mail, which means that the same problems exist for e-mail and DeltaChat. Furthermore, DeltaChat is not meant to replace the normal e-mail, but to provide an option for short messages.

 Isn't e-mail transfer slow?

No. Transferring messages that do not leave the university server (i.e. both e-mail addresses end with usually takes less than 2 seconds. If the message comes from or is transferred to external servers, the run time increases slightly. This then depends on the runtime of the external server.

 Why do I only receive late notifications, or none at all, about new messages?

DesktopClient: Problems are known and will be fixed. (See: Github issue #1063)

Android: Newer Android phones in particular try to prevent apps from running in the background. This can cause new messages to appear late or not at all. The developers are trying to improve this in future versions. As a user, you can often tackle this yourself: see 

iOS: iOS tries to prevent apps from running in the background, which can cause new messages to appear late or not at all. The developers are trying to improve this in future versions. Users can make sure that DeltaChat is allowed to run in the background (Settings → General → Background Updates and enable DeltaChat).

 Where can I find my messages in Outlook?

All chat messages from DeltaChat are automatically moved into a "DeltaChat" folder in your inbox.

 Why are some DeltaChat messages not moved from the inbox?

To move the messages, the DeltaChat client must be active and able to connect to the mailbox. You can create a custom rule to always directly move these messages (see next section). Improvements and a "global" solution are being worked on.

 How do I create a rule for moving DeltaChat messages? (Outlook)

Using a "Rule" in Outlook, you can automatically move all DeltaChat messages directly into the DeltaChat folder:

Double check the phrase that the rule should search for: if you use the app in another language this could vary.

If the folder does not exist, you may have to create a new 


 Why can't I read messages from another person?
  • You may no longer be able to read messages because they are encrypted end to end (also see "Why can't I read some chat messages in my e-mail client (Outlook)?")
  • If you want to use DeltaChat on your mobile and desktop at the same time, please read "Using desktop and mobile clients at the same time: synchronising clients" above.
  • If you have reinstalled DeltaChat and only use one device, you can send a new message via DeltaChat to the appropriate person so that your new key is transferred. You can ask for the content of the last message at the same time.
 What does the message "Changed setup for e-mail address" mean?

This person's key has changed. This problem means that the person has reinstalled the DeltaChat client without transferring the old key (see "Using a new device" above).

 Where do all the contacts in the DeltaChat address book come from?

After installing the app, you will be asked if DeltaChat is allowed to access your private contacts. If you allow this, all contacts with an e-mail address will be added to the DeltaChat address book.

Additionally, DeltaChat will add the e-mail addresses of all people who either send or receive a message from you. In the future, only people with access to DeltaChat messages will be added to the address book (in progress).

 Why can I not see existing chats after reinstalling DeltaChat?

Only newly received messages are checked by DeltaChat. As soon as a new message is received in a chat, the group or contact will also appear in DeltaChat.

 What does the blue tick in the contacts mean? What does verified mean?

The blue tick means that the contact has been verified and has a key (for end-to-end-encryption. It was additionally confirmed separately to the e-mail traffic that it really is this person (e.g. scan of a QR code). Only verified persons are allowed in verified groups.

 I can't see my sent messages on my second device

Desktop Client: In DeltaChat → Options, activate "Send copy to self".

Mobile Client: In DeltaChat → Settings → Advanced, activate "Send copy to self".


 Is my communication encrypted?

As with normal university e-mails, the connection from application to server and server to application is always encrypted. In addition, end-to-end communication is encrypted as soon as all participants in the chat use DeltaChat.

 What does "end-to-end" encryption mean?

Messages can only be decrypted by devices with the appropriate key. Messages are encrypted from the sender device to the receiver device and cannot be viewed on the server.

 How do I know if my communication is end-to-end encrypted?

For end-to-end encrypted messages, a small padlock symbol will appear before the date:

 Why can't I read some chat messages in my e-mail client (Outlook)?

This is due to the end-to-end-encryption. To edit DeltaChat messages in the desktop client, please read "Using desktop and mobile clients at the same time: synchronising clients" above.

 When are my messages end-to-end encrypted?

As soon as all participants in a chat use DeltaChat, all communication is automatically end-to-end encrypted. This applies to both group and 1-to-1 chats.

 My message is not end-to-end encrypted. Why could that be?

This suggests that at least one participant does not use DeltaChat or his key is not yet known. For new contacts, the key is exchanged when the first message is sent. Only then can the communication be end-to-end encrypted.


 My question was not answered. What can I do?

Even more information is available on the developer's official help page:
If you still have questions, please contact the support service (see below).


If you have any questions please send an e-mail or DeltaChat message to:

Data Backup / Hosting

Because DeltaChat is based on e-mail, all information provided for E-Mail and Calendar is relevant here

Request Service

Access to this service does not have to be requested.