This is an incompatible fork of https://github.com/mschneider82/milter, which is an excellent update to github.com/phalaaxx/milter.

API / Interface

The present API is not guaranteed to be stable though any changes will be minimized.

There were quite a few iterations as code using this evolved to get it to it's present state and now various projects depend on the interface not breaking.

Fork-Specific Changes

• The interface has been altered from mschneider82's code such that it's now easier to determine the boundaries between messages.

• The session and message IDs have been removed, they can be implemented in the specific Milter code if needed.

• A small race in .Close() has been fixed.

• Macros accumulate/mutate throughout the session and are now usable.

• Testing; updated for new API. Milter is no longer embedded in the TestMilter as it's not necessary or desirable.

• At least one chance after this was forked has been ignored so far (IPv6 addresses are working as expected for me, if a change is made to trim the IPv6 prefix is should probably only be done after checking it exists).

Rough Guide to the Lifecycle of Calls

NewSession is called at the start of milter session. EndSession is called when it's closed.

Connect is called once per session, it contains the string (name) of the remote host and it's address information.

Helo is called one (or more) times per session in response to HELO or EHLO.

Reset can be called at almost anytime to reset message-specific state, this corresponds to SMTPs RSET verb.

NewMessage is called before an email message is to be delivered. Usually you will see one message per session, but it's possible for there to be zero or two or more. Some high-performance MTAs will reuse SMTP connections so that you will see multiple messages from difference sources to different addresses in a given session.

MailFrom is called for MAIL FROM, one of which per message.

RcptTo is called for RCPT TO, one or more of which per message.

Header is called for head header passed in to the BODY stage of SMTP transaction.

Headers is called upon completion of all headers.

BodyChunk is called (possibly many times) with parts (chunks) of the message BODY.

Body is called upon completion of the entire BODY.

Example Sessions

Macros

Macros are available from some function at milter.Modifiers.Macros, these accumulate and mutate throughout the session. Some macro values are valid for the duration of the session, some are only valid for the current or previous message. The lifecycle of macros is not well defined, this usually isn't a problem for session level state but for things that change per-message use with care.