Exim on EC2

When you configure your Exim on an EC2 server, remember to set the hostname or it'll use Amazon's internal, private unresolvable name. Here's what I did for the Profoss newsletter server configuration in exim.conf:

primary_hostname = newsletter.profoss.eu

This resolves this kind of error messages in you mainlog file:

Recipient address rejected: No IP address found for HELO/EHLO domU-12-31-35-00-39-A1.z-2.compute-1.internal - try again later