Some customers have asked us why we require you to configure an SPF record, when all that we're doing is forwarding emails, not sending them from your domain.
However, this is not actually technically correct. We are, in fact, sending emails from your domain name when we forward emails to you.
This is because of the method that we use for email forwarding, called SRS (Sender Rewriting Scheme).
You can read the Wikipedia article above for a full explanation, but to put it simply, this is how our service works when we forward an email:
- We receive the email that is addressed to you, eg an email from [email protected]
- We then rewrite the email headers on that email to be from an auto-generated address, that includes the sender email, on your domain, eg [email protected]
- As a result, the email provider that we're delivering your email to treats it as if the email was from your domain, not from facebook.com
If we didn't use Sender Rewriting Scheme, the emails we forwarded to you would likely fail and land in your spam box, because our IPs would not be included in Facebook's SPF allow list, and therefore would end up in your spam folder.
This is why we require you to configure a TXT/SPF record, to ensure that your email provider trusts the messages that we forward to you.
