Hey devs!

I'm hitting a problem when migrating from 2.1 to 3, but I think it's a generic issue (or rather a missing feature) and I'd like to fix it.

If I try to associate an existing address to an existing user (without this address obviously), the Mailman API will reply with a 400 error "User already exists". Postorius currently does not detect that and just errors out with a 500 page (but that's not the issue here).

I think I need to merge the two users, and that's currently not supported. I believe it would be a useful feature, so I'd like to discuss it here. IMHO, the only tricky part would be to merge the preferences associated with each user, but if I know which of my two users has priority, I can just resolve the conflicts that way. Am I missing something? Do you agree it would be a useful feature to have?

Aurélien