I have school email account that gets forwarded to my gmail account, which I have setup as an IMAP with Mac Mail. I am using the Mac mail client in Snow Leopard and am having trouble getting the "From" address feature to work. I want to be able to send messages from my forwarded email address through gmail in Mail.

Some messages do successfully get sent from my school account but most do not. I have already setup a second outgoing server on my email client, but that doesn't seem to be the problem. I am not exactly sure what is going wrong and what is different when it does send the message from the address I want.

I would really like to solve the issue so that I can send school emails from Mail and not have to go to the website to reply or send new messages. This would be the easiest and fastest way because my school does not support POP/IMAP.