Identifying An Unresponsive Mail Delivery Service
If one or more of your MTAs is online but not sending or receiving email, there is likely a problem with one of your mail delivery services. In order to fix the problem, you will need to first identify the unresponsive service. Use the following steps to help identify the source of the problem.
To find an unresponsive mail delivery service:
- 1. Beginning with Postfix (ports 25 & 10025), and working through Amavisd (port 10024) and Tomcat (port 7025), use the following command to check for responsiveness:
telnet localhost <port>
- 2. If the service is responsive, it shows the server banner.
Trying 127.0.0.1 Connected to localhost.localdomain (127.0.0.1) Escape character is ‘^]’. 220 hostname.domain.com ESMTP Postfix
- If the service is unresponsive, you see a response that looks like this:
Trying 127.0.0.1 Connected to localhost.localdomain (127.0.0.1) Escape character is ‘^]’.
- Without seeing something similar to this with the above response:
220 hostname.domain.com ESMTP Postfix
- Note: If you receive the following response from any of these queries, your MTA is offline entirely.
Trying 127.0.0.1... telnet: connect to address 127.0.0.1: Connection refused telnet: Unable to connect to remote host: Connection refused
- 3. Continue checking your services until you find the unresponsive one.
Once you have identified the unresponsive service, you will need to do more troubleshooting to resolve the issue. For more information on mail delivery services, see the Related Topics below.