Sendpost, nosendpost, copysendpost, errsendpost Channel Options

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Returned messages (sendpost, nosendpost, copysendpost, errsendpost)

A channel program may be unable to deliver a message due to long-term service failures or invalid addresses. When this happens the MTA channel program returns the message to the sender with an accompanying explanation of why the message was not delivered. The MTA will also optionally send a copy of certain failed messages to the local postmaster. This is useful for monitoring message failures, but it can result in lots of traffic for the postmaster to deal with.

The options sendpost, copysendpost, errsendpost, and nosendpost are used to control the sending of failed messages to the postmaster. sendpost tells the MTA to send a copy of all failed messages to the postmaster unconditionally. copysendpost instructs the MTA to send a copy of the failure notice to the postmaster unless the originator address on the failing message is blank; i.e., the postmaster gets copies of all failed messages except those messages that are actually themselves reporting on bounces or other notifications. errsendpost instructs the MTA to only send a copy of the failure notice to the postmaster when the notice cannot be returned to the originator. No failed messages are ever sent to the postmaster if nosendpost is specified.

The default in releases prior to Pasilla was copysendpost. As of Pasilla the default has been changed to nosendpost.