I have strange problem with my SPF records and gmail MX. I have this SPF setup
v=spf1 a mx ip4:IP1 ip4:IP2 include:_spf.google.com ~all
In this case, if I send an email to two specific domains, also using gmail MX, I got emails bounced back. With message:
Message will be retried for 1 more day(s)
Technical details of temporary failure: The recipient server did not accept our requests to connect. Learn more at http://support.google.com/mail/bin/answer.py?answer=7720 [(0) smtp.my_company.com. [IP2]:587: Connection refused]
This happens only if I send mail to two specific domains, like "theshelf.com" and "icloud.com". I have made firewall rule to log connections to 587 port and indeed google tries to connect every time I try to send email to these domains when IP2 is in SPF. Remedy for this is to remove IP2 from SPF record. But what use of remedy if I dont understand why it is happening :). Thing is I may not need IP2 in SPF at all, but that is not issue, issue is why google tries to connect to IPs that are in SPF record, and just for some domains.