My mail server supports an infinite number of aliases per mailbox:

accountname(\-[a-z0-9.\-]+)*@mydomain.invalid

The SMTP server accepts these aliases as "From" (after authentication with my main mailbox credentials).

Is it possible to tell kmail to use the "To" header as new "From" on reply? It seems as if it always uses the identity address

I don't think it can be done automatically (but I have never investigated how identity aliases - configured in identities - work).

Hm, seems to be a bug?

I have a shared inbox for all of my accounts and if I receive a mail at me@provider and reply to it kmail wants to send the reply even from an other identity and a totally different account (other-me@different-provider).

The identity aliases seems to do nothing and the documentation says nothing about them.


Update: https://bugs.kde.org/show_bug.cgi?id=360963