prepare code for hanling setuid/chroot in external table backends.
disabled for now since it requires changes in the bootstrapping
Prepare for setuid/chroot in external queue process.
Does not work for now. Need to tweak bootstrapping.
missing include
only remove the incoming dir if running in server mode
Document how the default server name is determined
Show one accept message per rcpt for the same message
Allow to restrict the address family used for smtp and mta in the
configuration file:

listen on <iface> [inet4|inet6] ...

limit mta [for domain my.domain] [inet4|inet6]
fix bug in envelope cache
Automatically detect if asr needs to be built along with smtpd
Do not schedule mta envelopes in batch.
Allow individual envelopes to be suspended in the scheduler.
Associated commands are:

smtpctl pause envelope <id>
smtpctl resume envelope <id>