Are you receiving the error ‘failed to start postfix mail transport agent’ while accessing Postfix?

Last week, we came across the same error ‘failed to start postfix mail transport agent’ due to which the emails of our customer was down for a long time.

At Bobcares, we always receive requests to fix such Postfix errors as a part of our Server Management Services.

Today, let’s discuss why this error occurs and see how our Support Engineers fix it.

Explore more about Postfix Mail Transport Agent

Before we get into resolving the error, let’s take a glimpse into what this postfix Mail transport agent is.

Postfix is one of the leading Mail Transfer agent which is used to send and receive emails. And the default port of Postfix is 25.

The best part is that postfix doesn’t need any configuration for strictly internal usage. Simply installing the package should suffice.

Root causes for ‘failed to start postfix mail transport agent’ error to occur and how we fix it?

Let’s now discuss the different causes of this error. And see how our Support Engineers fix it.

1. A bug in the Plesk

We recently received a request from one of our customer who was using Plesk. He came with an error that the Postfix was not working. Here is the error message.

failed to start postfix mail transport agent

Our Support Engineers started troubleshooting this problem and found that there was a bug in the Plesk.

Now, let’s take a look at how our Support Engineers fixed this error.

Initially, we made a directory using the command:

mkdir /etc/systemd/system/postfix.service.d/

Secondly, we created the configuration file.

touch 10-start_limit_interval.conf

Then we ran the below command to add a directive to 10-start_limit_interval.conf.

StartLimitInterval='0' > /etc/systemd/system/postfix.service.d/10-start_limit_interval.conf

After that, we reloaded the unit files and restarted postfix.

systemctl daemon-reload
systemctl start postfix.service

Finally, this fixed the error.

2. Permissions problem

We received a request on the same error from another customer. He received the error during boot time. Here is the error message

systemd: Starting Postfix Mail Transport Agent...
systemd: postfix.service: control process exited, code=exited status=1
systemd: Failed to start Postfix Mail Transport Agent.
systemd: Unit postfix.service entered failed state.

Let’s see how our Support Engineers troubleshoot this error and fix it.

We ran the below command to start the Postfix

systemctl start postfix
journalctl -xe

And here is the output.

But still, the errors were present in the log files.

Then, we went checking if the SELINUX is enabled on the server. For that, we ran the command:

sestatus

As a result, we could find that the SELINUX was active. So we tried to disable it. And then we restarted postfix.

systemctl restart postfix

Finally, this fixed the error in Postfix.

[Need any assistance with Postfix errors? – We’ll help you]

Conclusion

In short, the Postfix errors are quite common. Fortunately, there are many ways to dig deep into the error and fix it. Today, we saw how our Support Engineers fix this error.