550 communication auth_error ai_generated partial

550 5.7.1 Service unavailable; Client host [x.x.x.x] blocked using Spamhaus

ID: communication/smtp-550-spamhaus-blocked

Also available as: JSON · Markdown · 中文
78%Fix Rate
86%Confidence
1Evidence
2023-01-20First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
Postfix 3.8 active — — —
Sendmail 8.17 active — — —
Exim 4.96 active — — —
Spamhaus SBL v2 active — — —

Root Cause

The sending IP address is listed in the Spamhaus Block List (SBL) or Exploits Block List (XBL), causing the receiving MTA to reject the connection as spam.

generic

中文

发送 IP 地址被列入 Spamhaus 阻止列表（SBL）或漏洞利用阻止列表（XBL），导致接收 MTA 拒绝连接，视为垃圾邮件。

Official Documentation

https://www.spamhaus.org/faq/section/Spamhaus%20BL%20Queries

Workarounds

  1. 70% success Check the IP against Spamhaus using: `dig +short x.x.x.x.zen.spamhaus.org`. If listed, visit https://www.spamhaus.org/lookup/ to request delisting after fixing the spam issue (e.g., securing the server from being an open relay). 
    Check the IP against Spamhaus using: `dig +short x.x.x.x.zen.spamhaus.org`. If listed, visit https://www.spamhaus.org/lookup/ to request delisting after fixing the spam issue (e.g., securing the server from being an open relay).
  2. 85% success Route outgoing mail through a trusted SMTP relay or service (e.g., SendGrid, AWS SES) that has a clean IP reputation. Configure Postfix: `relayhost = [smtp.sendgrid.net]:587` with credentials. 
    Route outgoing mail through a trusted SMTP relay or service (e.g., SendGrid, AWS SES) that has a clean IP reputation. Configure Postfix: `relayhost = [smtp.sendgrid.net]:587` with credentials.
  3. 60% success If the IP is static, contact the ISP or hosting provider to request a new IP address and update DNS records accordingly. 
    If the IP is static, contact the ISP or hosting provider to request a new IP address and update DNS records accordingly.

中文步骤

  1. Check the IP against Spamhaus using: `dig +short x.x.x.x.zen.spamhaus.org`. If listed, visit https://www.spamhaus.org/lookup/ to request delisting after fixing the spam issue (e.g., securing the server from being an open relay).
  2. Route outgoing mail through a trusted SMTP relay or service (e.g., SendGrid, AWS SES) that has a clean IP reputation. Configure Postfix: `relayhost = [smtp.sendgrid.net]:587` with credentials.
  3. If the IP is static, contact the ISP or hosting provider to request a new IP address and update DNS records accordingly.

Dead Ends

Common approaches that don't work:

  1. Change the sender email domain to a different one 92% fail

    Changing the sending domain does not affect the IP reputation; the block is based on the IP address, not the domain.

  2. Add SPF and DKIM records to the sending domain 88% fail

    Adding SPF/DKIM records does not remove the IP from the blocklist; the block is at the IP level and requires delisting.

  3. Restart the SMTP server (Postfix/Sendmail) 95% fail

    Restarting the MTA does not change the IP's blocklist status; the IP remains listed until delisting is requested.