I was running a website on a shared hosting account. Part of this website involved sending a lot of messages via PHP mail(). Unfortunately, all shared hosting providers I could find had a cap on how many emails could be sent per hour.
So, I decided to get a VPS. I am cheap, so I thought I would get an unmanaged one with cpanel. Everything is fine and dandy, I have everything up and running. The only problem I have, is that every message sent by php mail takes about 30 seconds to send. The same thing happens when I send via the PEAR SMTP package. Takes about 30 seconds, and sends three times.
It could be a DNS issue, I had no idea how to set it up, so I guessed:
A-type: @ smsalertsonline.com 18.104.22.168
MX entry: @ smsalertsonline.com - Mailer-server: smsalertsonline.com
Could it be a problem with sendmail? Is something not configured properly? Exim?