Templating master.cf

[Matt Saladna]

Hello all,

I provide a base master.cf part of an RPM release that I'd like to give 
users the ability to customize without overwriting each RPM release. Use 
case would be allowing per-sender bind/helos using 
sender_dependent_default_transport_maps or setting content milters 
beyond the basics the RPM provides.

postmulti is one approach to this, but requires duplication of main.cf. 
Further updates or reconfiguration to main.cf would need to be 
propagated to each multi instance. Servers may be running over 50 
sender-dependent SMTP services, which can add unnecessary overhead.

Are there any downsides with shipping master.cf.in + Makefile, adding a 
install/update hook to make master.cf (cat master.cf.in master.cf.local 
> master.cf)? Users could store their per-server overrides in 
master.cf.local, master.cf.in would be distribution, and master.cf 
continues to live happily ever after. Any other approaches to explore as 
well?

- Matt