SPF stands for Sender Policy Framework and is an email validation protocol designed to detect and block email spoofing by providing a way for email clients to verify that incoming mail from a domain comes from an IP Address authorized by that domain's administrators.

SPF is one of the most important mechanisms for email deliverability and is required to authorize Amply to send email on your organization's behalf.

SPF Alignment

SPF alignment is when your Return-Path (also know as Mail From or Envelope From) domain matches the Header From domain. The two types of SPF alignment are relaxed alignment and strict alignment. If you do not specify strict alignment, relaxed alignment is assumed.

Relaxed Alignment

With relaxed alignment, only the root domain of the return-path must match the root domain of the Header From address. Relaxed alignment allows a subdomain to be used and still meet the domain alignment requirement.

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Valid Alignment

If your Return-Path domain is mail.example.com and your Header From is example.com, your email would pass SPF alignment. The root domains example.com match.

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Invalid Alignment

If your Return-Path domain is example.mail.com and your Header From is example.com, your email would not pass SPF alignment. The root domains mail.com and example.com do not match.

Strict Alignment

With strict alignment, the domain of the Return-Path must be an exact match for the domain of the Header From address.

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Valid Alignment

If your Return-Path domain is mail.example.com and your Header From is mail.example.com, your email would pass SPF alignment. The domains example.com match.

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Invalid Alignment

If your Return-Path domain is mail.example.com and your Header From is example.com, your email would not pass SPF alignment. The domains mail.example.com and example.com do not match.

Setting your SPF Domain

In order to determine if the email server is authorized to send mail from that address, an email client will look up the DNS record for yourdomain.com. When you verify your domain, you'll need to set a DNS record at amp.yourdomain.com.

This record is a simple CNAME record and may look something like this:

NAME amp.yourdomain.com IN CNAME "yourhost.smtp.sendamply.net"

The above SPF record authorizes Amply to send email on behalf of yourdomain.com. As long as the server sending email matches this domain, the email will pass the SPF check. If not, the email client will be unable to verify the sender identity and will most likely flag your email as spam.