Feature: add connection_in/out_id

[bjne]

connection_in/out_id variable, similar to message_exim_id in
global uniqueness. connection_out_id is preserved between
deliveries, and available in event actions.

[HeikoSchlittermann]

Bjørnar Ness <notifications@github.com> (Sa 22 Feb 2020 01:01:25 CET):

connection_in/out_id variable, similar to message_exim_id in global uniqueness. connection_out_id is preserved between deliveries, and available in event actions.

Sounds great. I'll have a look at it. Maybe we can merge this into a joined attempt to create a id early in the incoming phase, and keep it throughout the spool- and delivery process. Having multiple IDs isn't the way to avoid confusion :) -- Heiko