There are a lot of undeliverable outgoing emails on my server and I see an error message that the postfix error mail transport is not available. . what should i do?
one of the typical postfix errors that creates a problem for many of our clients.
The mail transport not available error occurs mainly due to a misconfiguration in the postfix configuration file.
At bobcares, we often receive requests to fix postfix bugs as part of our server management services.
Today, let’s dive into the details and see how our support engineers fix postfix errors like mail transport not available.
the main reason postfix error mail transport is not available
In the business world, there has been a growing need for a Linux mail server. thanks to postfix mail server which is reliable mail server for your business needs. In addition, it acts as a mail transfer agent that transfers mail from the server to other servers, in the smtp protocol.
frequently, postfix clients may face errors like mail transport not available while managing postfix mail servers. the main reason for this error is misconfiguration of postfix.
fixes for postfix error mail transport not available
at bobcares, where we have over a decade of server administration experience, we see that many customers face issues managing postfix mail server.
Now, let’s look at the main reasons for errors related to this suffix and how our support engineers fix the main errors.
1. typos in variables
Recently, one of our customers had a problem with a recently configured postfix mta. when she tried to start the suffix the following warning appears.
postfix/qmgr[7288]: warning: connect to private/amavis transport: connection refused dsn=4.3.0, status=deferred (mail transport not available)
While checking /var/log/mail.log, our support engineers found an incorrect setting in the master.cf configuration file. it was a typo.
for example,
here, our client had mistakenly set as no_unknown_recipient_check in /etc/postfix/master.cf file instead of “no_unknown_recipient_checks”. therefore, the typo caused a misconfiguration in the postfix file and blocked it from working properly.
so, we changed no_unknown_recipient_check to no_unknown_recipient_checks and fixed the problem. also, we make sure that the settings given in the postfix config are correct or not.
Also, whenever we change files in /etc/postfix, you can always run postmapon on the file to update it. otherwise postfix doesn’t update an existing one.
the basic synopsis is,
that’s all.
2. bad postfix setting
Similarly, several plesk server owners complain that their emails are stuck in the mail queue, resulting in a large number of outgoing emails not being delivered to the plesk server.
Checking the mail log in /var/log/maillog, we can see the following error.
postfix/qmgr[14111]: warning: connect to private transport/xxx.xx.x.xx-: connection refused postfix/error[21724]: 0a1322cf16c: to=james.doe@example.com, relay=none , delay=0.07, delays=0.03/0.01/0/0.02, dsn=4.3.0, status=deferred (mail transport not available)
therefore incorrect transport configuration can lead to the above error. then, this can be edited via tools & settings > mail server settings. and, while running the following command, we can also see the configuration.
Next, we check /etc/postfix/master.cf where the sdd_transport_maps are defined in the first column of the smtp_bind_address option.
Also, in order to connect, smtp_bind_address must be defined as mentioned in the mynetworks section. for plesk versions higher than 12.0, the mynetworks variable must be empty.
again, we whitelist ip addresses in plesk > tools and settings > mail server settings > whitelist tab. if so, they will be added to the mynetworks section.
postfix mail configuration on plesk server appears as:
finally, we restart the service.
this is how we solve the problem.
3. problems with loft
Similarly, another client had a problem receiving emails after configuring postfix and dovecot on his ispconfig server. received an error like,
postfix status=deferred (mail transport not available)
Often, problems with receiving emails can occur due to misconfiguration of dovecot on the server. this is because dovecot is responsible for receiving emails from the server to local systems. delivers emails from the server to thunderbird in imap or pop3 protocol.
upon verification, our support engineers found that the client had configured as shown below,
but it was not correct.
so we change as follows.
this resolved the error.
[need help correcting the suffix error? we will help you.]
conclusion
In short, an error like postfix error mail transport not available can occur due to misconfiguration in postfix configuration file. today, we saw how our support engineers fixed bugs related to postfix.