Port creation

[Steve Shockley <steve_(_dot_)_shockley_(_at_)_shockley_(_dot_)_net>]

I'm working on a port for Courier-MTA, and I've got a couple of 
relatively generic porting questions.

Courier requires a spool/state directory.  The current Courier-IMAP port 
places it in /var/run/courier-imap, but the Postfix port puts it in 
/var/spool/postfix.  Should an MTA spool directory go under /var/run or 
/var/spool?

Courier includes a tool to update configuration existing configuration 
files to add any applicable new default entries.  This is 
non-destructive, in that Courier will ignore any options it doesn't 
understand, should the end-user wish to downgrade.  Courier's "port 
builder's instructions" suggest running the tool at the end of the 
installation.  If the config files don't exist, it generates them.  The 
advantage to this is that an installation/upgrade is completely 
automatic (i.e. the user doesn't have to merge config files), the 
disadvantage is this breaks @sample and an uninstall won't automatically 
remove config files that haven't been modified.  (On the other hand, 
since the tool creates the default config files, there aren't any 
default files to install via @sample at install-time.)

Should I run the tool at install time, or just tell the user to run it?

Is creating /etc/mailer.conf.xxx (as Postfix does) the preferred/correct 
way to allow the user to replace Sendmail?

Thanks.