When a mail server stops accepting connections or mail flow becomes intermittent, the problem can come from many layers: DNS, network, firewall, mail server software (Zimbra, Postfix), TLS certificates, or even system resources. This guide walks through practical, step-by-step troubleshooting techniques for Zimbra and Postfix connection issues, shows commands you can run immediately. This blog gives you a detailed guide to troubleshoot similar issues. If facing trouble in receiving mail from outside, you need to find out where the message is failing. While sending test message, you need to check …
