Interesting. Have you looked at this?
https://serverfault.com/questions/133190/host-wildcard-subdomains-using-post...
[People have too much "flair" and rep points and I can't participate in those stackexchange discussions or ask or answer like I used to.]
On October 27, 2021 3:15:01 PM AKDT, dovecot@ptld.com wrote:
I think your approach would work, however, if I set up aliases similar to:
@barbaz.mydomain.com -> barbaz@mydomain.com.
I believe I can do that in postfix with some regex magic.
Yes, that would work perfectly without any regex. You just point the catchall alias to the "user". @barbaz.mydomain.com -> barbaz@mydomain.com
one stumbling block could be that we don't know the various subdomains ahead of time.
The subdomain can be any value that the user wants, and we don't want them to have to precreate them before they can use an address
Best to my knowledge this is not possible with postfix. But ask the postfix mailing list to get a definitive answer. In postfix you have to tell it the domains it accepts mail for, anything else it considers relaying. Otherwise how does postfix know that email is meant to be saved here or it is just passing through and you want postfix to query DNS to find out where it goes (if relaying is even allowed).
The purpose of the system is that users can create disposable/temporary email addresses for various testing jobs.
Are you aware of postfix recipient_delimiter? It allows for disposable / wild card addresses. If enabled in postfix, you setup a mailbox user like barbaz@mydomain.com and any address with that user and the delimiter would still get delivered to that user.
barbaz@mydomain.com -> barbaz@mydomain.com barbaz+randomtext@mydomain.com -> barbaz@mydomain.com barbaz+test1@mydomain.com -> barbaz@mydomain.com
You can change the + to any symbol you want postfix to look out for.
I think my "creating users" was me wanting to make sure that when postfix passes an email for "barbaz@mydomain.com" to Dovecot, then Dovecot will store it and wait for someone to come along and impersonate barbaz. i.e. "barbaz" doesn't have to exist as a user already before Dovecot will store the mail.
If you are using LMTP dovecot will only accept emails from postfix that it can lookup the /directory/path to from one of the userdb{} or passdb{} sections. If dovecot can not find a match in any of the userdb{} or passdb{} it will reject the email as user unknown causing postfix to send a undeliverable notice email back to the envelope sender address, also known as back-scatter. I am not aware of a way to use wildcard addresses in dovecot userdb{}, i don't think its possible but i don't know what i don't know.
-- Sent from my Android device with K-9 Mail. Please excuse my brevity.