exim4: multiple domains/IPs

Question

On my VPS I have 3 IPs which all have their own domain and their own reverse-DNS records. I have a website on each domain, sending emails.

The problem is: the emails are rejected by many hosts because the reverse dns doesn't fit the host in the helo. All the emails are sent from the primary IP and therefore only one of the three domains work.

I am looking for a way for exim to check which email adress i'm using to send the email and adapt the domain/IP transmitted in the helo.

I have already tried many configurations but nothing has worked up to now. Simply changing MX-Records is impossible too, as I recieve (and also send) email via gmail and I don't want to set up my own webmail.

Does anyone know a solution?

Answer 1

The simple solution is to configure one address in the interface definition, and use it's domain name in the helo message. If you use SPF, allow this address to send mail for all three email domains. Its domain does not need to match any of the web servers. MX records are for incoming mail, and your MX does not need to be the address your email originates from.

Automated mail servers tend to be poorly configured and cause me no end of problems. I applaud your efforts to get it right. Please make sure your outgoing email is properly formatted with all the necessary headers.

Often the simplest thing to do is to use the MX for the web server's domain as a smarthost for the web server. It is fairly easy to routing rules for different domains. In this case you would use the sender_address_domain to select the routing.