Mails from this box are sent via smarthosts picked up by sender.
In other words.
1. mail is put into queue with "sendmail -f ..." command
2. according to sender_dependent_default_transport_maps is picked up
smarthost and mail is route via this smarthost.
And assume we do not use "-f" flag when call sendmail.
Is it possible to set sender based on "From:" message header, in case
when "envelope from" is empty?
I think that it is something to do with canonical_maps, but I am not