iRedMail — Single user is having external email bounced as no user

Re: Single user is having external email bounced as no user

null@example.com (SteveInAkron) — Tue, 07 Oct 2025 13:37:52 +0000

Here's the output of the command:

catchall_maps.cf
domain_alias_catchall_maps.cf
domain_alias_maps.cf
recipient_bcc_maps_domain.cf
recipient_bcc_maps_user.cf
relay_domains.cf
sender_bcc_maps_domain.cf
sender_bcc_maps_user.cf
sender_dependent_relayhost_maps.cf
sender_login_maps.cf
tracy@zzzzzz.ccc
transport_maps_domain.cf
transport_maps_maillist.cf
transport_maps_user.cf
virtual_alias_maps.cf
tracy@zzzzzz.ccc
virtual_mailbox_domains.cf
virtual_mailbox_maps.cf
vmail1/zzzzzz.ccc/t/r/a/tracy-2025.09.09.17.13.47//Maildir/

I found a work around by adding every email address to a recipient_access file and adding the line

check_recipient_access hash:/etc/postfix/recipient_access,

to the smtpd_recipient_restrictions

It started to happen with other users of other domains, so it's not a single user anymore.

Still want to find the cause, so any more tips are appreciated.

It's back to working now, but I haven't removed my fix yet.

I think the problem may be with something my cloud provider did with their networking.

Re: Single user is having external email bounced as no user

null@example.com (ZhangHuangbin) — Sun, 05 Oct 2025 03:18:49 +0000

Please show us full console output of commands below (replace tracy@zzzzzz.ccc by real email address):

cd /etc/postfix/mysql/
for i in $(ls *.cf); do echo $i; postmap -q tracy@zzzzzz.ccc mysql:./$i; done

Re: Single user is having external email bounced as no user

null@example.com (SteveInAkron) — Sat, 04 Oct 2025 12:58:22 +0000

User exists. The domain was transferred to the server about a month ago, and has been working fine until 9:30AM yesterday.

The issue is with the interaction between the external SPAM filter service and my server. I changed the MX record for the domain to eliminate the external filter for now, and it is working. I use the external filter for a few other domains that are working fine.

I had debug_peer_list on for the domain before I changed the MX, but didn't see anything obvious.

I did change the mailbox quota for that user the day before, but I cannot see how that would have an effect.

Re: Single user is having external email bounced as no user

null@example.com (ZhangHuangbin) — Sat, 04 Oct 2025 02:56:56 +0000

Does user "tracy@zzzzzz.ccc" exist? If not, it's expected that Postfix rejects it.

Single user is having external email bounced as no user

null@example.com (SteveInAkron) — Fri, 03 Oct 2025 20:32:26 +0000

==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.6.8 MARIADB edition
- Deployed with iRedMail Easy or the downloadable installer? Installer
- Linux/BSD distribution name and version: Debian 12
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): NginX
- Manage mail accounts with iRedAdmin-Pro? Yes
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

A single user from a domain is having all mail to them bounce with a message similar to the below. It is only for this single user. The user can receive mail from other users on the server.

2025-10-03T15:54:06.027957-04:00 iredmail postfix/smtpd[1810471]: NOQUEUE: reject: RCPT from xxxxx.yyyyy.net[w.x.y.z]: 550 5.1.0
: Sender address rejected: User unknown; from= to= proto=ESM
TP helo=

I was going to add the user again, but I didn't want to loose the email.