On 2024-03-02 at 04:45:53 UTC-0500 (Sat, 2 Mar 2024 10:45:53 +0100)
Gerben Wierda via Postfix-users <[email protected]>
is rumored to have said:

Aliases are nice, to receive mail. But when you reply, the address behind the alias is exposed.

To prevent that I need to create full mailboxes, which requires a lot of administration in dovecot, postfix.

Suppose
- I am [email protected]
- At evilcompany.com they know be by my alias [email protected]
- I am mailing with [email protected]

Is there a way to create a lightweight 'reverse alias' for a specific target. E.g., suppose my alias is

meatevilcompany:        me

then have a mail from [email protected] to [email protected] turn into a reply from [email protected] to [email protected], but only for [email protected] or for @evilcompany.com?

There is a commonly-used header that supports MUAs handling this: X-Original-To

Postfix will add that to mail it is delivering locally by default. It also adds a Delivered-To header with the final result of aliasing.

Some MUAs (I think this included TBird but I have not used it regularly in many years) can be configured to recognize those and compose replies as being "From: " the X-Original-To address, using the Delivered-To to figure out what account the reply should use for determining outbound server & auth.

This seems like it is much more suited to the MUA rather than a MTA/MSA. I don't think I want something on the server responsible for rewriting headers to keep their original content confidential when the user's MUA could have just written the proper public address there in the first place. I've been working with mailing lists this way for years on Eudora, Mulberry, TBird, and now MailMate. I reply to a message with an X-Original-To header and the MUA uses that address to compose and send the message.

--
Bill Cole
[email protected] or [email protected]
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Not Currently Available For Hire
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