Package addr includes IDNA aware address structs.

Package header includes interfaces to access and modify email headers.

Package testtrx can be used to test mailfilter based filter functions.

New creates and starts a new [MailFilter] with a socket listening on network and address.

WithDecisionAt sets the decision point for the [MailFilter].

WithErrorHandling sets the error handling for the [MailFilter].

WithoutBody configures the [MailFilter] to not request and collect the mail body.

AcceptWhenError accepts the transaction despite the error (it gets logged).

The DecisionAtConnect constant makes the mail filter call the decision function after the connect event.

The DecisionAtData constant makes the mail filter call the decision function after the DATA event (all RCPT TO were sent).

The DecisionAtEndOfHeaders constant makes the mail filter call the decision function after the EOH event (all headers were sent).

The DecisionAtEndOfMessage constant makes the mail filter call the decision function at the end of the SMTP transaction.

The DecisionAtHelo constant makes the mail filter call the decision function after the HELO/EHLO event.

The DecisionAtMailFrom constant makes the mail filter call the decision function after the MAIL FROM event.

Error just throws the error.

RejectWhenError rejects the transaction (and logs the error).

TempFailWhenError temporarily rejects the transaction (and logs the error).

Trx can be used to examine the data of the current mail transaction and also send changes to the message back to the MTA.

DecisionAt defines when the filter decision is made.

DecisionModificationFunc is the callback function that you need to implement to create a mail filter.