Domain alignment is important for Domain-based Message Authentication, Reporting & Conformance (DMARC) to work properly. Domains out of alignment may cause the DMARC check to fail.
DKIM alignment is when your email's parent domain of the DKIM signing domain matches the Header From domain.
The two types of DKIM alignment are relaxed alignment and strict alignment. Relaxed alignment is assumed if you don't specify the type of alignment, but you can change your DMARC record to require strict alignment using the adkim tag.
Relaxed alignment
This alignment type requires the DKIM domain to match the parent Header From domain. Relaxed alignment is the default. Relaxed alignment allows a subdomain to be used and still meet the domain alignment requirement.
Examples:
- If your DKIM domain is mail.example.com and your Header From is example.com, your email would pass DKIM alignment.
- If your DKIM domain is example.mail.com and your Header From is example.com, your email would not pass DKIM alignment.
Strict alignment
This alignment type requires the DKIM domain to match the Header From domain exactly.
Examples:
- If your DKIM domain is mail.example.com and your Header From domain is example.com, your email would not pass DKIM alignment.
- If your DKIM domain is mail.example.com and your Header From domain is mail.example.com, your email would pass DKIM alignment.
