Exim

begin routers
...
local_user:
        debug_print = "R: local_user for $local_part@$domain"
        driver = accept
        domains = +local_domains
        #check_local_user
        transport = dovecot_lmtp
        cannot_route_message = Unknown user
...
begin transports
...
dovecot_lmtp:
        driver = lmtp
        socket = /var/run/dovecot/lmtp
        #maximum number of deliveries per batch, default 1
        batch_max = 200
        #allow suffixes/prefixes (default unset)
        rcpt_include_affixes
...

Dovecot
Прим.: не работает со static userdb

auth_username_format = %Ln
...
protocols = imap pop3 lmtp
service lmtp {
    unix_listener lmtp {
      #mode = 0666
   }
}
...
userdb {
  driver = passwd
}
passdb {
  driver = pam
  #args = dovecot
}
...