Mac Mail receiving but not sending. smtp not working
I have been using Mac Mail with my Gmail account without any trouble for the last few years and just for the last 2-3 weeks I cannot send any e-mails. I am receiving without any problems, but no matter what I do it won't send, not even an e-mail to myself. My Calendar is set up to send my notifications and those won't even go. I have verified my settings (time and time again), I deleted and reset-up my account, in the last two weeks I have done everything I can, but can't figure it out so I am getting kind of desperate. I am sure that it is something to do with smtp but all of my settings for that are right too (in accordance to the Gmail and Apple sites). What I have done is just read and responded to my e-mails (when I do it offline) and then I have to log into my gmail account and copy/paste ALL of my e-mails manually, which I am sure you can imagine is extremely inefficient. Thank you to anyone who can help!
Running Mac OS X 10.6.8 with Mail 4.5 and accessing Gmail
MacBook, Mac OS X (10.6.8)