add handlers for SMFIR_ADDRCPT, SMFIR_DELRCPT and SMFIR_CHGFROM

[bokutin]

Hello.

I modified it to do the postsrsd equivalent process with milter.

It was easy because authentication_milter itself is well structured.

It works well in my environment.

I would be happy to merge it if it is useful.

However, there is no test, and if you are worried about maintenance, you don't have to merge it.
In that case, please reject and close.

Thanks.

[marcbradshaw]

My main issue here is there is no associated change in the SMTP protocol handler, so running this in SMTP mode will result in methods being called which do not exist. This is a reasonable feature, but needs SMTP support and tests.

[bokutin]

You are right. Thanks for the reply!