PHP mail not showing up at Gmail but shows up at Hotmail and other 3rd party/ISP account

Question

I have 2 sites where mail is sent to two vanity gmail accounts. I\'m using PHP to handle the mail, but the mail is not showing up at gmail (not in spam/junk, it just doesn\

Answer 1

I've found having a proper SPF record for your domain really helps

http://www.openspf.org/SPF_Record_Syntax