[ISSUE] mrep: Use first instead of last delivered-to to set from address

[ISSUE] mrep: Use first instead of last delivered-to to set from address

[xelxebar]

[-- Attachment #1: Type: text/plain, Size: 1300 bytes --]

New issue by xelxebar on mblaze repository

https://github.com/leahneukirchen/mblaze/issues/233

Description:
## Overview

Commit e1e5bfe5 introduces a regression against 282de650. In cases where there are multiple `Delivered-To` headers, it is most likely that we want `mrep` to populate the sender address from the most public-facing `Delivered-To`, *i.e.* the first one; however, at the moment we are setting it to the address in the final (*i.e.* topmost and most internal-facing) one.

## Why?

We have a posix setup that aliases multiple addresses into a virtual mailbox---*e.g.* all mails going to `mars.*@example.com` get glommed into `mars@example.com`. The problem is that postfix aliases end up adding an additional `Delivered-To` header for each of these alias redirections. This is necessary to detect alias loops and related problems.

## Patch points

This proposed change boils down to munging [mcom:377](https://github.com/leahneukirchen/mblaze/blob/master/mcom#L377). I believe we just need to reverse the order of headers passed to `maddr` and then `tail -n 1` instead of `head -n 1`. However, it appears that `maddr` doesn't currently have a `-M` switch like `mhdr`, so maybe a patch there is needed as well?

## Comments

Thoughts? Does the above sound reasonable?

Re: mrep: Use first instead of last delivered-to to set from address

[xelxebar]

[-- Attachment #1: Type: text/plain, Size: 187 bytes --]

New comment by xelxebar on mblaze repository

https://github.com/leahneukirchen/mblaze/issues/233#issuecomment-1529342095

Comment:
@leahneukirchen @stacyharper Mind weighing in on this?

Re: mrep: Use first instead of last delivered-to to set from address

[stacyharper]

[-- Attachment #1: Type: text/plain, Size: 333 bytes --]

New comment by stacyharper on mblaze repository

https://github.com/leahneukirchen/mblaze/issues/233#issuecomment-1529487343

Comment:
About the use case I had, I only had one Delivered-To. If the fix continue to pick it, rather than the useless To, it is okay to me. Choosing the first Delivered-To seems okay and predictable to me

Re: mrep: Use first instead of last delivered-to to set from address

[leahneukirchen]

[-- Attachment #1: Type: text/plain, Size: 307 bytes --]

New comment by leahneukirchen on mblaze repository

https://github.com/leahneukirchen/mblaze/issues/233#issuecomment-1529745903

Comment:
I guess both could be argued for, e.g. if you have multiple alias expansions they'll all end up as a Delivered-To..

I agree that maddr should parse repeated headers.

Re: mrep: Use first instead of last delivered-to to set from address

[leahneukirchen]

[-- Attachment #1: Type: text/plain, Size: 203 bytes --]

New comment by leahneukirchen on mblaze repository

https://github.com/leahneukirchen/mblaze/issues/233#issuecomment-1529751201

Comment:
I also found multiple mailing lists ending up as Delivered-To...

Re: mrep: Use first instead of last delivered-to to set from address

[Anachron]

[-- Attachment #1: Type: text/plain, Size: 485 bytes --]

New comment by Anachron on mblaze repository

https://github.com/leahneukirchen/mblaze/issues/233#issuecomment-1782500962

Comment:
Jumping on this, I received a mail on an account I've put into my `Alternate-Mailboxes` setting but when replying to it via mrep it reverts the `From:` to default. 

Is there a setting which lets me always use the `To:` address if it's inside the `Alternate-Mailboxes` setting? I couldn't find such a thing inside `mcom`.

If not, I may open a PR.