554 5.7.1 communication auth_error ai_generated true

SMTP 554 5.7.1 Transaction failed: message content rejected as spam

ID: communication/smtp-554-transaction-failed-spam

Also available as: JSON · Markdown · 中文
83%Fix Rate
86%Confidence
1Evidence
2024-03-05First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
Postfix 3.7.0 active — — —
Exim 4.96 active — — —
Microsoft Exchange Online active — — —
SpamAssassin 4.0.0 active — — —

Root Cause

Receiving mail server rejects the message because its content or headers trigger spam filters, often due to high link-to-text ratio, suspicious keywords, or missing DMARC policy alignment.

generic

中文

接收邮件服务器拒绝邮件，因为其内容或标头触发垃圾邮件过滤器，通常是由于链接与文本比例过高、可疑关键词或缺少 DMARC 策略对齐。

Official Documentation

https://www.rfc-editor.org/rfc/rfc5321#section-4.2.5

Workarounds

  1. 85% success Review and sanitize email content: remove excessive links, avoid spammy keywords (e.g., 'free', 'click here', 'urgent'), and ensure a balanced text-to-image ratio. Use a spam testing tool like Mail-Tester to pre-check. 
    Review and sanitize email content: remove excessive links, avoid spammy keywords (e.g., 'free', 'click here', 'urgent'), and ensure a balanced text-to-image ratio. Use a spam testing tool like Mail-Tester to pre-check.
  2. 80% success Configure DMARC policy to 'p=reject' or 'p=quarantine' and ensure SPF/DKIM alignment passes: verify the 'From' domain matches the DKIM signing domain and SPF envelope sender domain. 
    Configure DMARC policy to 'p=reject' or 'p=quarantine' and ensure SPF/DKIM alignment passes: verify the 'From' domain matches the DKIM signing domain and SPF envelope sender domain.
  3. 90% success Use a dedicated email sending service (e.g., SendGrid, AWS SES) with pre-warmed IPs and built-in spam compliance to handle content delivery, bypassing direct SMTP. 
    Use a dedicated email sending service (e.g., SendGrid, AWS SES) with pre-warmed IPs and built-in spam compliance to handle content delivery, bypassing direct SMTP.

中文步骤

  1. Review and sanitize email content: remove excessive links, avoid spammy keywords (e.g., 'free', 'click here', 'urgent'), and ensure a balanced text-to-image ratio. Use a spam testing tool like Mail-Tester to pre-check.
  2. Configure DMARC policy to 'p=reject' or 'p=quarantine' and ensure SPF/DKIM alignment passes: verify the 'From' domain matches the DKIM signing domain and SPF envelope sender domain.
  3. Use a dedicated email sending service (e.g., SendGrid, AWS SES) with pre-warmed IPs and built-in spam compliance to handle content delivery, bypassing direct SMTP.

Dead Ends

Common approaches that don't work:

  1. 60% fail

    Whitelisting the sending IP in the receiving server may bypass spam filters temporarily, but the message content itself remains flagged, leading to eventual rejection or quarantine.

  2. 80% fail

    Adding more DKIM signatures (e.g., multiple selectors) doesn't address content-based filtering and may confuse the receiving server's authentication chain.

  3. 70% fail

    Reducing the sending rate (e.g., 1 email per minute) doesn't change the message content; spam filters still evaluate each message independently.