# Unexplained Email::Receiver::InvalidPost errors

**URL:** https://meta.discourse.org/t/unexplained-email-invalidpost-errors/377793
**Category:** Bug
**Created:** [August 7, 2025, 8:31pm UTC](https://meta.discourse.org/t/unexplained-email-invalidpost-errors/377793 "2025-08-07T20:31:32Z")
**Posts on this page:** 1
**Showing post:** 37

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### Author: ![lavamind](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/lavamind/32/237909_2.png) [@lavamind](https://meta.discourse.org/u/lavamind)
#### Post date: [February 4, 2026, 6:36pm UTC](https://meta.discourse.org/t/unexplained-email-invalidpost-errors/377793/37 "2026-02-04T18:36:06Z")

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> [@Mirroring a read-only mailing list in Discourse](https://meta.discourse.org/t/mirroring-a-read-only-mailing-list-in-discourse/77990/1):
>
> The piece that you _might_ be missing is this one:
> 
> > [@Mirroring a read-only mailing list in Discourse](https://meta.discourse.org/t/mirroring-a-read-only-mailing-list-in-discourse/77990/1):
> >
> > Set “Custom incoming email address” to the mailing list’s email address (e.g., `mailing-list@foo.test`)
> 
> (remember that Discourse only uses the message headers (To/CC) and does _not_ know the envelope-to address)

For the tor-relays category, I have `Custom incoming email address` set to `tor-relays@lists.torproject.org` which I believe matches the `To:` header of the mails sent out by Mailman.

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