This error basically occurs due to bad-configuration of SPF record
record should be set to
"v=spf1 include:_spf.google.com ~all"
You can check for other errors at : https://toolbox.googleapps.com/apps/checkmx/
How to set SPF Record
1. Login to Godaddy or Cloudflare DNS Setup page
2. Create SPF Record like this.
Done.