MTA channel counters

The MTA has facilities to collect and monitor channel counters based upon the Mail Monitoring MIB, RFC 2789 (which updates RFC 1566). These counters tabulate on a per channel basis the twelve items described in  Table of channel counters from MADMAN MIB.

The MTA also supports some additional channel, association, and arbitrary counters; see this more extensive list at Table of MTA counters.

An MTA block is, by default, 1024 bytes. However, this size may vary from system to system. The size of an MTA block is controlled with the  MTA option.



 1. An MTA block is, by default, 1024 bytes. However, this size may vary from     system to system. The size of an MTA block is controlled with the      MTA option. 

 2. rejected_volume does not generally capture the entire volume of the messages rejected by the channel. Depending upon when, during attempted message submission, the rejection occurs, little to none of the message content and size may have been transferred (or made known) to the channel. 



It is important to note that these counters generally need to be looked at over time noting the minimum values seen. The minimums may actually be negative for some channels. Such a negative value merely means that there were messages queued for a channel at the time that its counters  were zeroed (e.g., the cluster-wide database of counters  created). When those messages were dequeued, the associated counters for the channel were decremented therefore leading to a negative  minimum. For such a counter, the correct "absolute" value is the current value less the minimum value that counter has ever held  since being initialized.

See also:
 * block_size MTA Option
 * directoryscan Option
 * Conversion channel
 * Sieve adjustcounter extension
 * MTA counters