This is beginning to annoy the hell out of me, I've been trying to resolve this issue for hours now. On this domain I setup I am using an external mailserver since my mail server is dedicated and separate, I used a similar setup for another domain and that works but for whatever reason this new domain I am working on doesn't send mail at all. Using a basic php mail test I get a 500 internal server error I checked to make sure that the domain and co-domain are both using the external mail server option, I also checked the local-host-names config file for sendmail to make sure the domain isn't present. Here are the maillog contents when I try my test: As you can see above it seems like for whatever reason it's trying to send it locally to itself when I use this domain which shouldn't be happening and I don't see how it is.... Any ideas anyone? TIA.