Outlook 2007, how to stop accidental replies from a certain folder?

Question

I have my college's email account auto-forwarded (they don't offer pop3 or imap) to my main gmail account so I don't have to go to their website to check for mail. That gmail account, and others, use pop3 down to my Outlook 2007. In my Outlook, I have a rule that puts mail sent to my @college address into a folder named Collegemail.

Since the college email system lacks pop3 or imap, I have to go to their site to send a reply, so that the reply will be sent from my @college email address. The problem is that since I don't get very many emails to that address, I cannot seem to get into the habit of going to my college's website to make those replies. So quite often I absent-mindedly make the replies while in Outlook, which means my replies are sent "from" the @gmail address that the @college emails were forwarded to.

I'm hoping there's a solution. Can I set up Outlook to either 1) disable replying to emails in the Collegemail folder or to emails where my college email address is in the original To: line, or else 2) set those replies to be sent using a non-functional dummy account? The dummy account would be unable to send the email so the email would be stuck in the Outbox. (I already have the non-functional dummy account set up as Outlook's "Default" account. When I compose a new mail I have to deliberately pick one of my good accounts to send the new mail with, or else Outlook uses the default dummy account and the email stays in the Outbox with a Send error.)

I have tried setting up the gmail "send email from another address" option and setting the account up in Outlook, and all that works, but that's not what I'm wanting because the receiver of my replies sees my reply's "From" line as: "[e-mail] On Behalf Of [e-mail]".  I need a way to prevent replies to emails that have me@collegemail in the original To: line before they're sent, so I can go to my college's website to send them from there instead of from Outlook.

I guess I am looking for a VBA solution.  But I don't know, of course.
Thanks.