I have a domain managed via Amazon's Route53 service. I have a Google Apps (free) account with 10 full users. To facilitate more than 10 users (we need about 12-14), I've been using a setup whereby extra users are represented as 'groups'. From time-to-time, however, they have problems sending/receiving mail, which is marked as spam. For each 'group', a normal gmail account is set up, and configured to receive mail from the group's email address, and send mail via Google's SMTP server.
For email sent from our site, we use Amazon's SES service.
I've tried a couple of online-spf checking services and the results look generally OK. However, I do have the following warning from Google's CheckMX tool:
There SHOULD be a valid SPF record.
SPF record specifies Gmail's IP addresses as valid for sending domain's messages If no other servers send mail on behalf of this domain then this record SHOULD be set to "v=spf1 include:_spf.google.com ~all"
My current SPF record reads:
"v=spf1 include:_spf.google.com include:amazonses.com ?all"
I'm not sure if this could be the cause of the problem; is there an adjustment I should make?