Verify your SPF record:

  1. Use the G Suite Toolbox to verify your SPF record. Go to https://toolbox.googleapps.com/apps/checkmx/.
  2. Enter your domain name
  3. Click Run Checks!
  4. When the test finishes, click Effective SPF Address Ranges.
  5. Check the SPF results. The results should include:
    1. _spf.google.com
    2. _netblocks.google.com followed by several IP addresses
    3. _netblocks2.google.com followed by several IP addresses
    4. _netblocks3.google.com followed by several IP addresses