Bounce block limit MTA option

Notification message and return job options
The  MTA option may be used to force  bounces of messages  over the specified size (number of blocks, as  defined via the   MTA  option) to return only the message headers, rather than the full  message content. This overrides any NOTARY (RFC 1891) setting originally present on original messages.

By default, there is essentially no limit; (more precisely, the default is the maximum allowed integer, 2&#x2a;&#x2a;31-1).

See also:
 * Notification message format
 * block_size MTA Option
 * Notification message MTA options
 * Message size MTA options