Enable delay timers MTA option

Counters MTA options:  (0 or 1)
The MTA can optionally maintain timers to measure delays caused by various external processes. Setting the  MTA option to a  value of 1 enables these  timers. A value of 0 (the default) disables them.

Timings are done on a per-message basis, if enabled. For details on what timers are available, see the  MTA option which discusses the details of the timers, as well as the format in which they may optionally be logged.

See also:
 * Counters MTA options
 * log_callout_delays MTA Option