SPF is a way for the receiver to validate if a specific sender is authorized to send mail on behalf of a specific domain. This is done via a DNS TXT record lookup.
To create a Google SPF record for a domain:
- Log in to the administrative console for your domain (where your DNS is hosted).
- Locate the page from which you can update the DNS records.
You may need to enable advanced settings.
- If you already have aTXT record set up for SPF, then modify the record to be the following, otherwise create a TXT record containing this text: v=spf1 include:_spf.google.com ~all
In order to validate your SPF record, you can use the following URL, which will check your current settings.