Final RCPT plugin

It may be of some use to add a config var that changes the behaviour of this plugin to call next with constants.OK vs just next.

In our use case, if it's found in the DB which has enough info to make decisions as to whether or not the user is enabled, do they accept msgs (what if it's a noreply@) etc, then we should process for receipt.

Before modifying the plugin, since this didn't give an OK, receiving failed. No other plugins are/were used for testing if proper for receipt.

I could probably submit a diff at some point along with a config var included, I'm only using github to submit an issue. I'd suggest naming the config var "authorative" and if set to true, it calls next with constants.OK .

Start with the plugin's current recipient-validation path and its handling of next; the issue requests a configuration option for the constants.OK behavior. Done means the option is documented and the plugin can use it to continue successful receipt processing when the database has enough recipient information.

Written by the indexing model from the issue text.