SUBMIT=ON activates processing of the [SUBMIT] block in the smtpd.cfg. You need to specify the port to listen on in this block. 587 is used by default because it is the officially assigned port for message submission, just like 25 is the well-known port for SMTP (look in /etc/services for a short list of well-known ports).
In swa.properties you put it as swa.email.smtpServer=hostname.domain:587. I prefer to use the hostname instead of localhost only, as I can then use port 587 to accept mail from the outside. If you put no RELAY rules in the [SUBMIT] section no mail will be accepted unless authentication has been done first, so it's nice to expose this to people travelling a lot and needing a SMTP host.
In my smtpd.cfg my [SUBMIT] is as follows:
[SUBMIT]
LISTEN=hostname.domain:587,localhost:587
# Reject all anonymous connections
ANONYMOUS Log_Reject ALL
lsof -i:25 gives me:
COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
sendmail 2643 root 4u IPv4 6908 TCP localhost.localdomain:smtp (LISTEN)
omsmtpd 2871 root 4u IPv4 7394 TCP host.domain:smtp (LISTEN)
Oh, yeah, if you change swa.properties and add a port to the SMTP server you need to be careful when running the installer. It doesn't recognise the format, so you have to put in the hostname without a port, then afterwards edit it by hand (
http://bugzilla.scalix.com/show_bug.cgi?id=14663)