# Is it possible to communicate with non-DC user? (interoperability with email) **URL:** \ **Category:** Mutual Help\ **Tags:** open-standards, chatmail\ **Created:** [December 8, 2025, 8:54am UTC](https://support.delta.chat/t/is-it-possible-to-communicate-with-non-dc-user-interoperability-with-email/4425 "2025-12-08T08:54:55Z")\ **Posts on this page:** 1\ **Showing post:** 9
**Author:** ![Minim](https://support.delta.chat/letter_avatar_proxy/v4/letter/m/ccd318/32.png) [@Minim](https://support.delta.chat/u/Minim)\ **Post date:** [December 14, 2025, 4:13pm UTC](https://support.delta.chat/t/is-it-possible-to-communicate-with-non-dc-user-interoperability-with-email/4425/9 "2025-12-14T16:13:11Z")
That feature req exists: [Prompt to switch to encrypted chat when it is available](https://support.delta.chat/t/prompt-to-switch-to-encrypted-chat-when-it-is-available/4010) Perhaps you could [file a feature request with K9](https://github.com/k9mail/k9mail.app/issues)? If K9 implemented the [SecureJoin standard](https://github.com/deltachat/securejoin) it would be easy to share keys securely between K9 clients, and K9 would also interoperate very well with [Deltachat](https://cosmos.delta.chat/); your testing has confirmed it. And there would be another excellent alternative to insecure key exchange. Completely separately, from what you’ve reported, K9 could allow users to automatically create free e-mail accounts on any standard Chatmail mailserver, from inside K9, by typing in the e-mail address they want (or just picking the domain). That might be an appealing feature. Alas, I can’t use K9, because I am on Mobian! So I can’t write up a step-by-step of configuring it. I take it enabling Autocrypt is pretty easy, though. * * * * * * * * * **EDIT** (because I technically can’t add a post) It seems client interoperability has gotten more problematic: > [@Document the minimum requirements necessary for chatmail interoperability](https://support.delta.chat/t/document-the-minimum-requirements-necessary-for-chatmail-interoperability/4853): > > I am currently working on Delta Chat interoperability for bower/notmuch ( [GitHub - wangp/bower: A curses terminal client for the Notmuch email system · GitHub](https://github.com/wangp/bower) , [https://notmuchmail.org](https://notmuchmail.org)). My goal is to support enough of the features Delta Chat uses that I can comfortably use my command line email setup to exchange messages with Delta Chat users. Currently, I am also using my command line setup in Multi Device Mode together with the Delta Chat Android app from F-Droid. A couple of days back, I ra… --- _[View the full topic](https://support.delta.chat/t/is-it-possible-to-communicate-with-non-dc-user-interoperability-with-email/4425)._