MTA Role

MTA Role#

This section provides details about the Carbonio MTA’s mail queues, how to interact with them, and how to extract relevant information.

Mail Queue Management#

There are cases in which messages that users send remain stuck in the outgoing queue and can not be delivered to the recipient. When this happens, you can check the MTA queue in different ways:

  • by executing some commands from CLI

  • from the Carbonio Admin Panel (see Section Queue)

  • by using Prometheus/Grafana based dashboards, on which suitable alarms can be defined

CLI commands available#

The following is a list of commands that can be used from the CLI. you can check their manpage for their use and configuration.

  • postconf is a Postfix command to view or modify the Postfix configuration

  • postfix is the main Postfix command, used to start, stop, and reload the service; flush the queues; check and upgrade the configuration

  • qshape allows to examine Postfix queues in relation to time and sender’s or recipient’s domains

  • postqueue is used to manage queues

  • postsuper allows to delete messages from queues (must be run as root)

  • postcat allows to read messages in queues (must be run as root)

Example
# /opt/zextras/postfix/sbin/postqueue -p|grep someString | awk \
'{print $1}' | /opt/zextras/postfix/sbin/postsuper -d -

This command filters from the queue all messages containing someString, then prints only the first field, which is the e-mail ID and passes to postsuper, which deletes the messag to the queue.

Daily E-Mail Reports#

If the MTA logs are concentrated on a single Carbonio Node by specifying a value for options zimbraLogHostname, it will be possible to define an entry in crontab that sends a daily report; for example, the following entry in crontab will generate a report every day at 11:30 PM:

30 23 * * * /opt/zextras/libexec/zmdailyreport -m

The report will contain a lot of useful information, including:

  • comprehensive statistics about the processed messages: received, delivered, forwarded, deferred, bounced, and so on

  • Host/Domain summary: message delivery (top 50)

  • Host/Domain summary: messages received (top 50)

  • Top 50 senders by message count

  • Top 50 recipients by message count

  • Top 50 senders by message size

  • Top 50 recipients by message size

  • Details about message deferral, bounce, andreject

Message tracking#

Carbonio makes available the zmmsgtrace utility: it allows to track the flow of messages, rebuilding it from the log files. Useful options are:

--id "msgid"  The e-mail ID of the message

--senders "john.smith\@example.com"    Rebuild the flow of all messages
                                       sent by john.smith\@example.com

--recipient "john.smith\@example.com"  Rebuild the flow of all messages
                                       received by john.smith\@example.com

All these options accept a regexp as value.

A more detailed help is provided by command

$zextras /opt/zextras/libexec/zmmsgtrace --help
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