you appear to be referring to the iTools account, and that is the port to which you connect, not the port from which you connect. The port to which you connect can not be changed, or you won't connect at all. If you make a pop account, you appear to be able to enter the port if you so desire.
I'm not sure if this helped, but if you did not get your answer from this reply, I suggest you expand on your problem.
well, I don't see any support for any such freaky port swapping in the mail app. My next thought would be to run NAT, and put in a specific rule for your that port incoming and outgoing. I forget the syntax for some of it, and it may screw you up royally if you're trying to use this machine as a server of some sort.
I'm assuming this isn't the kind of solutian you're looking for. If it is, let me know and I'll walk through some of it and see what I can do with self nat port mapping. right now I'm sleepy. Good luck.
You appear to be mixing up sending and receiving protocols. SMTP is the sending protocol and it uses port 25. Unfortunately this can't be changed in Mail in 10.1.
IMAP uses port 143 by default and POP uses port 110 by default. Both of these are receiving protocols only. If you need to use an IMAP account on port 108 you can change that port on the Account Options tab. But that's only for receiving, not sending.
As far as I've heard, Microsoft will not be bringing Outlook Express to Mac OS X as it feels the free email client application needs are fufilled by Apple's mail. If you want to run a Microsoft emai client, you'll have to buy office and use entourage.