On 2019-11-22, Ralph Seichter via dovecot <dovecot@dovecot.org> wrote:
- Robert via dovecot:
We use a simple system for routing emails to different email users by postfixing the addresses with the actual user: xxxJohn@domain; yyyJohn@domain etc all will be delivered to user John. (This way John can invent a new email address on-the-fly and that will be delivered to his email box.)
But now you can't have a username like "BigJohn@domain". To avoid this problem a separator character of some sort (that isn't used in a normal email address at your site) is really wanted.
This seems like a strange way achieve flexible email addresses. Are you aware of sub-addressing? It has been around for ages, and is supported by Dovecot (and Gmail, incidentally).
Imagine an existing email account <alice@example.com>. If alice wants to use a subadress, she signs up with <alice+foo@example.com>, and Dovecot can automatically place incoming mail for that address into INBOX/foo (or just INBOX if INBOX/foo does not exist). Alice can use as many sub-adresses as she needs without anybody making config changes.
This method works well, but the separator character can be a problem. "+" is traditional, but is widely blocked by website validators - if you can use "-" or "." instead they're much more likely to be accepted.