I came across a problem today where Exim4 was just freezing messages in the queue.

When i unfroze one and tried to send it i got the following error message:

“R=nonlocal: Mailing to remote domains not supported”

A quick search showed that this was a configuration issue caused by Exim not being set to send mail to external locations. Thankfully this could easily be changed by running:

“dpkg-reconfigure exim4-config”

This will bring up a step by step config walk threw that you can use to make the needed changes. On the first option select :

“internet site; mail is sent and received directly using SMTP”

Finish the config and try and resend the messages.

Useful commands:

unfreeze a single message: exim -Mt messageid
unfreeze the entire queue and resend: exim4 -qff
remove all frozen messages: exiqgrep -z -i | xargs exim -Mrm

For more tips i recommend the following site with a good cheat sheet:
Exim Cheat sheet

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