MAIL: Can receive but not send emails. It is an application file problem - NOT passwords, ports, etc.
I have been using Mail for years. Out of the blue, several months ago, I stopped being able to send emails from ANY of the 4 different email accounts I use. All of them can still receive. My 4 accounts are all from different sources (Gmail, workplace 1, workplace 2, yahoo) . All the passwords are correct, etc. This occurs regardless of where or how I access the internet.
I read somewhere a while ago that some operating system file (I don't really know the right terminology) related to Mail must be corrupted, but I cannot find that information now. Also, fixing system files is not something I am comfortable delving into without detailed instructions because (I'll admit it straight up) that is above my skill level.
Any help would be greatly appreciated! This is driving me nuts
MacBook Pro, Mac OS X (10.6.8)