Possible to rewrite SMTP username on send before sending to DB/memory for validation?

[ghost]

Is there a way to rewrite the incoming username SMTP is authenticating with on sends, before sending it off to SQL/memory for validation in order to support on-the-fly anonymous emails? I scanned the manual but did not see this.

More detail: What I'd like to do is an implementation of "on the fly" or "anonymous" email addresses -- ones that can be made up on the spot while you're filling in somebody's webform. I see that I can use a regex to rewrite the incoming recipient addresses, like:

catch-all = { map = "otf(.+)@example.com$", to = "[email protected]" }

which would rewrite, for example, [email protected] -> [email protected], which is where I would receive it. Good. Now I want to support replying to the received email. To do this I need SMTP to authenticate "[email protected]" as "[email protected]", because the email will be sent from otftesting123. Is this possible?

[mdecimus]

There is no need to rewrite the authenticated username in this case. You can authenticate as [email protected] and send emails as [email protected] and vice-versa.