Correct SPF Record Usage?

Question

My txt entry for my domain is as follows:

txt --> "v=spf1 a ip4:aspmx.googlemail.com ptr:aspmx.googlemail.com include:aspmx.googlemail.com -all"

I have also tried to use 'ptr' in addition to 'a', however, I'm not sure I fully understand the difference between them. PTR seems to do a reverse lookup on the domain, where as A simply references the A record in the zone file?

The header response from gmail is:

Received-SPF: unknown (google.com: domain of do-not-reply@mydomain.com uses a mechanism not recognized by this client. unknown mechanisms: ))

Authentication-Results: mx.google.com; spf=permerror (google.com: domain of do-not-reply@mydomain.com uses a mechanism not recognized by this client. unknown mechanisms: )) smtp.mail=do-not-reply@mydomain.com; dkim=neutral (no key) header.i=@mydomain.com

Thanks for any suggestions.

Answer 1

The correct TXT record for googlemail is "v=spf1 include:aspmx.googlemail.com ~all". You should also note the usage of ~all versus -all.

Answer 2

Please see this page: Please see this page from Google: http://support.google.com/a/bin/answer.py?hl=en&answer=178723

Publishing an SPF record that uses -all instead of ~all may result in delivery problems. See >Google IP address ranges for details about the addresses for the Google Apps mail servers.

EDIT: You should also really be using DKIM. With DMARC standardization approaching, this is highly important.