I have a PHP Helpdesk web app installed on our Intranet server. Part of the job of the Helpdesk is to send e-mails to Users to keep them up to date with calls. The setup is quite simple and you have to enter an SMTP address into the call in order to send these updates.
We have two domains. The SMTP Server (Exchange 2010) is a different server to the web app server, which is running IIS.
When a call is added/updated and the e-mail address of the User is on the same domain the e-mail works OK. But when we're trying to send to the other domain (for which mail must go out before it comes into the second domain) it fails to be relayed.
i.e. email@example.com works, but firstname.lastname@example.org does not.
I don't know how to set up PHP Mail and have no idea if it would break things anyway.
I know that the web server can send SMTP to email@example.com because an ASPX page that sends out passwords works OK to that domain.
I've looked around, but I can't figure out where the issue may lie! :(