aspf tag
The DMARC tag choosing relaxed (r, the default) or strict (s) alignment between the SPF-authenticated MAIL FROM domain and the From domain.
What it means
With aspf=r, an SPF pass for bounces.example.com aligns with a From address at example.com. With aspf=s, the MAIL FROM domain must equal the From domain exactly. Many sending platforms use a dedicated return-path subdomain, so strict SPF alignment breaks them unless the From address uses the same subdomain.
Like adkim, aspf is optional, and RFC 9989 notes that nearly all domain owners find relaxed alignment sufficient. Remember that SPF alignment cannot exist without an SPF pass: if SPF fails, the alignment mode does not matter.
Example
v=DMARC1; p=quarantine; aspf=sRelated terms
On this site
Sources
What this definition rests on. The wording is ours; the facts are theirs.
- RFC 9989: Domain-based Message Authentication, Reporting, and Conformance (DMARC), section 4.7rfc-editor.org
- RFC 9989: Domain-based Message Authentication, Reporting, and Conformance (DMARC), section 4.4.2rfc-editor.org
- Google Workspace Admin Help: Set up DMARCknowledge.workspace.google.com
All 432 terms in the glossaryThe wiki: blocklists and bounce codes