I have friend with Mac OS X version 10.3.7. After the system was upgraded to v10.3.7 he could not longer send email. Internet access is fine. Receiving emails works fine. I suspect it has something to do with MTU settings but am not sure. Any help out there?
Are there any error messages, delivery failure notices, or does the email just never arrive?
Have you checked the settings for outgoing mail server details in Mail preferences?
Also, try deleting the account settings in Mail.app and re-create them.
