Introducing Automatic E-mail Address Porting (AEAP)

The Delta Chat 1.32 releases introduced e-mail porting mechanisms (AEAP). They enable for e-mail what number porting does for mobile phone communications, i.e. to more easily change between communication providers.

How it works under the hood

Nothing immediately happens after you successfully changed to your new e-mail address in the settings screen. No network activity or sending of messages is taking place. Your internal identification and encryption keys stay the same and are not altered¹. Your contacts don’t know yet that you changed your address yet and will continue to send messages to your old address. For this reason, you better configure your old email provider so that it forwards all emails to your new email address. Otherwise messages sent to your old address won’t arrive because Delta Chat does not try to retrieve messages from there after the change. If you don’t know how to setup e-mail forwarding for your old provider please ask on the Support Forum.

If you send a message to any chat, the other chat members will not complain if they see it coming from your new e-mail address. They might see a “~” in front of your address and would then still reply to your old e-mail address. This is why it’s important to configure e-mail forwarding on your old provider. Things are smoother, however, if you send a message to a “verified group chat” because recipients there will automatically update to your new e-mail address and not send chat messages to your old e-mail address anymore! Verified groups are a an experiemtal but pretty stable feature of Delta Chat. Verified groups have blue tickmarks and members can only join after verifying with a pre-existing member. See COUNTERMITM protocols for more details.

What do we aim to improve about AEAP?

In subsequent releases we hope to make the e-mail address rewriting also happen for non-verified groups. For this we need to harden generic e-mail authenticity verification to the point of enabling AEAP for all encrypted chat groups (verified or not).

We are generally colloborating with maintainers of mailcow, a popular docker-based distribution for self-hosted e-mail. We might add a way to register “e-mail forwarding” so that moving from a mailcow-server instance to another provider would be seemless and would not require the manual provider-specific step of “setup forwarding of mails to your new address”. We would be down to “change your e-mail adddress” and incrementally all (chat) e-mails will flow to your new provider.

After gathering more experience, we may also suggest additions to the Autocrypt encryption standard such that account-migration could be more safely implemented by e-mail apps other than Delta Chat.

Special thanks to NLNET and their Next-Generation-Internet work

The work on AEAP is already ongoing for well over a year (on and off) and has been funded through the NLNET foundation, in turn funded by the European Commission. We particularly like to thank Michiel, Jos and the rest of the NLNET NGI team for smooth handling of advising, reporting and financing.

For those who know a bit more about PGP: Not altering the identification and encryption keys means that the UID field of your PGP key will not be changed and still contain the old address. This is a design choice to keep things simple, and it’s possible because Autocrypt says that “the content of the user id packet is only decorative” (https://autocrypt.org/level1.html#openpgp-based-key-data). ↩

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