Local email delivery issues

Hi there,
I trust you are well.

I am experiencing some issues with local email delivery. I have a domain on an ISPConfig 3 server, which only uses the web service. DNS and Mail are handled externally.

However, when sending mail to the domain from a mailbox hosted on the ISPConfig 3 server, the mail rejects immediately with:

Sending of the message failed.
An error occurred while sending mail. The mail server responded:
<info@[domain]>: Recipient address rejected: Domain not found.
Please check the message recipient "info@[domain]" and try again.

I believe this is because the ISpconfig 3 server is attempting to deliver locally, and is not finding a mailbox for the domain, rather than delivering to the server as per the external DNS server.

How does one resolve this issue.

 

Hi Till,
I trust you are well.

The recipient domain is not added to ISPConfig as an email domain at all. Only as a web domain. The sender is however added as an email domain, as I use the ISPConfig server for the sender domain.

I seem to have fixed it however by creating a DNS zone within ISPConfig and adding a record pointing to the external mail server.

 

I see. Okay I'll remove the zone as DNS is handled externally.
The /etc/resolv.conf file contains only:

# cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
# 127.0.0.53 is the systemd-resolved stub resolver.
# run "resolvectl status" to see details about the actual nameservers.

nameserver 127.0.0.1

Should I add our nameservers here?

 

That worked.
For anyone wanting to know how to add nameservers to Debian 12 using resolvconf;
Edit the /etc/network/interfaces file:

Code:

# vim /etc/network/interfaces

Add your nameservers under the gateway line. Be sure to match the indent syntax (iface stanza):

Code:

  ...
  gateway 162.xx.xx.xxx
  dns-nameservers 129.xxx.xxx.xx xxx.xxx.xx.x
  # route xxx.xx.xxx.xxx/xx via xxx.xx.xxx.xxx
  ...

Note: nameserver ip addresses are separated by a single space.
Restart the Network deamon with:

Code:

# systemctl restart networking.service

Test your changes:

Code:

# cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
# 127.0.0.53 is the systemd-resolved stub resolver.
# run "resolvectl status" to see details about the actual nameservers.


nameserver 129.xxx.xxx.xx
nameserver 68.xxx.xx.x