I'm trying to send mail using either the built-in PHP mail() function or through the phpmailer library, which of course relies on mail(). phpmailer says it "cannot instantiate the mail function" so I'm troubleshooting directly through mail(). I do have mail() working correctly elsewhere, but the address is internal (same domain as web server, also the mail server is on the same LAN as the web server) so I'm sure that's why the it works and my new function doesn't. Here's the error log (and no, icWALL is not a typo, that's exactly how it copy/pasted):
[17-Jul-2013 11:37:27] PHP Warning: mail() [<a href='function.mail'>function.mail</a>]: Unable to send message to SMTP server. 5.5.1 Error: need RCPT command icWALL (188.8.131.5221)
I'm thinking it's a SonicWALL config issue, but I've never heard of RCPT before. Is there a workaround in PHP, such as authenticating? Or do I need to have them change configs on the SonicWALL?
The system is an IBM iSeries running Apache (not sure the version), PHP 5.3.8, and Zend Server extensions. It is pretty similar to Linux as far as PHP is concerned, so go ahead and try to answer as if it were Linux if you have any idea.