Error codes

The bounce the receiver sent. The page title is that text.

• 550 5.7.26 This email has been blocked because the sender is unauthenticated. Gmail requires all senders to authenticate with either SPF or DKIM.Gmail blocked the message because the sender was not authenticated. It requires SPF or DKIM.
• SPF PermErrorPermError means the domain's published SPF records could not be correctly interpreted. RFC 7208 says that requires DNS operator intervention.
• DMARC alignment failedSPF or DKIM can pass on a domain that is not the From domain. DMARC still fails, because alignment is a separate check against the address the reader sees.
• SPF too many lookupsSPF evaluation must stop at 10 DNS-querying terms. Past that, the result is permerror. The message is not a soft fail.
• 550 5.7.27 This message was blocked because it didn't pass SPF authentication. Gmail requires bulk email senders to authenticate their email with SPF.Gmail blocked the message because SPF did not pass. Bulk senders have to authenticate with SPF.
• 550 5.7.30 This message was blocked because it didn't pass DKIM authentication. Gmail requires bulk email senders to authenticate their email with DKIM.Gmail blocked the message because DKIM did not pass. Bulk senders have to authenticate with DKIM.
• 550 5.7.40 Your message was blocked because the sending domain doesn't have a DMARC record or the DMARC record doesn't specify a DMARC policy.Gmail blocked the message because the sending domain has no DMARC record, or the record has no policy. Bulk senders have to publish DMARC.
• 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.
• 550 5.7.25 This message was blocked because the sending IP address doesn't have a PTR record, or the forwarding DNS entry doesn't reference the sending IP address.Gmail blocked the message because the sending IP has no PTR, or the name in that PTR does not point back at the IP. Gmail requires a PTR on sending IPs.
• 550 5.7.29 This message was blocked because it wasn't sent over a TLS connection.Gmail blocked the message because the SMTP session was not TLS. Bulk senders have to use TLS/SSL for SMTP.
• 550 5.7.24 The SPF record of the sending domain has one or more suspicious entries.Gmail blocked the message because it treats one or more terms in the sending domain's SPF record as suspicious.
• 550 5.7.1 This message does not meet IPv6 sending guidelines regarding PTR records and authentication.Gmail blocked the message because the IPv6 sending path did not meet its PTR and authentication rules.