The postfix plugin reports metrics on the postfix queues.
For each of the active, hold, incoming, maildrop, and deferred queues (http://www.postfix.org/QSHAPE_README.html#queues), it will report the queue length (number of items), size (bytes used by items), and age (age of oldest item in seconds).
[[inputs.postfix]]
## Postfix queue directory. If not provided, telegraf will try to use
## 'postconf -h queue_directory' to determine it.
# queue_directory = "/var/spool/postfix"- postfix_queue
- length (integer)
- size (integer, bytes)
- age (integer, seconds)
- postfix_queue
- queue
postfix_queue,queue=active length=3,size=12345,age=9
postfix_queue,queue=hold length=0,size=0,age=0
postfix_queue,queue=maildrop length=1,size=2000,age=2
postfix_queue,queue=incoming length=1,size=1020,age=0
postfix_queue,queue=deferred length=400,size=76543210,age=3600