SMTP Error: RCPT TO command failed Rejected because xxx.xxx.xxx.xxx is in a black list at zen.spamhaus.org Error – Hestiacp | Solvedlinux solvedlinux, September 10, 2024September 10, 2024 If you’re managing an email server and experiencing email bounces with a message like: SMTP Error: RCPT TO command failed: Rejected because [your IP] is in a blacklist at zen.spamhaus.org Error: open resolver; https://check.spamhaus.org/returnc/pub/67.205.148.18/ 550 Then your IP address may have been flagged by Spamhaus. Even if your IP isn’t listed directly on Spamhaus, this error can still occur due to issues like an open DNS resolver.Spamhaus keeps a number of blacklists, such as the zen.spamhaus.org list, that identifies IP addresses that are used for spamming or other illegal activities. These lists are used by a lot of email servers to filter out unsuitable messages. Servers that use these lists will refuse your emails if your IP address is blacklisted.Since you’re dealing with an open resolver issue in this instance, third parties may be able to utilize your server for illegal activities due to DNS settings on your server. You can verify by clicking on the link in the bounce message to see if your IP address is mentioned. Starting SMTP test of: server.solvedlinux.com Resolved IP address to: 68.183.134.110 Connection: opening to 68.183.134.110:25, timeout=15 Connection: opened < 220 server.solvedlinux.com SMTP connection established > EHLO www.solvedlinux.com < 250-solvedlinux.com Hello node-server.solvedlinux.com [112.134.153.50] 250-SIZE 52428800 250-8BITMIME 250-PIPELINING 250-CHUNKING 250-STARTTLS 250 HELP > MAIL FROM: < 250 OK > RCPT TO: < 550-Rejected because 139.162.157.118 is in a black list at zen.spamhaus.org 550 Error: open resolver; https://check.spamhaus.org/returnc/pub/67.205.148.18/ SMTP ERROR: RCPT TO command failed: 550-Rejected because 112.134.153.50 is in a black list at zen.spamhaus.org 550 Error: open resolver; https://check.spamhaus.org/returnc/pub/67.205.148.18/ SMTP Error: RCPT TO command failed Rejected because 112.134.153.50 is in a black list at zen.spamhaus.org Error: open resolver; https://check.spamhaus.org/returnc/pub/67.205.148.18/ 550 Fixing Email Bounce Issue Due to Spamhaus Blacklist (zen.spamhaus.org) - Hestiacp You can easily get fix this issue by temporarly removing zen.spamhaus.org from exim dnsbl.conf. To do that you can open ssh terminal and run above command. Copy sed -i '/zen/d' /etc/exim4/dnsbl.conf systemctl restart exim4 Uncategorized