CiviCRM Community Forums (archive)

Gmail doesn't have any whitelisting or Feedback Loop setup or any other way to directly engage with them regarding deliverability, they mostly go by spam reports by users as well as the subject and content of the email.

For example Gmail will look at your subject line for some red flag words, for example they might consider it spam if it has words like "Free" or "Important".  Some experts say they  also look at engagement by your audience so they recommend removing people from your bulk mailing list if they haven't opened or otherwise engaged with your emails in the last 6-9 months.

Some also recommend suggesting to your users in the header of the email that they add you to the contact list - emails from contacts on the contact list do not get marked as spam.

Another thing you can do is instruct your users to mark your emails as "Not Spam" with a short set of instructions or a screenshot on how to do that.

SPF records help with deliverability in general not only with Gmail but with all providers.
If you are using a custom domain (not a domain that we provided to you) then we recommend you set up SPF records and here are instructions on how to do that:

http://civismtp.com/drupal/faq#spf

If you are using a domain we provided to you such as orgname.uas.coop or orgname.civismtp.org then your domain already has SPF records set up.