Do you have any other email addresses you could use to send tech support an email? Yahoo, Hotmail, whatever? If you could get one, then try using another email program, like Outlook Express, to retreive any responses from tech support.
But if I were you, I would be on the phone with my ISP's tech support people, not emailing them.
Also, you could try re-installing Netscape. Maybe some file got corrupted and a re-install will set it right.
And usually, to be able to troubleshoot a computer problem, it helps to have version numbers of your operating system and whatever appllication is involved. For some problems, though probably not in this case, it helps to know the type of computer you have.