421 5.7.32 Your email was blocked because the From: header (RFC5322) in this message isn't aligned with either the authenticated SPF or DKIM organizational domain.

Gmail blocked or rate-limited the message because the From domain did not align with the SPF domain or the DKIM domain.

Google also prints 421 5.7.32 as a rate limit: the From header is not aligned with the authenticated SPF or DKIM organizational domain.

Both rows on the SMTP error list, last updated 18 September 2026 UTC, use SMTP 421 and status 5.7.32. Alignment is the DMARC check. SPF's domain is MAIL FROM. DKIM's domain is d=.