Can’t contact certain servers

I have a client who connects to the web ok, but even though her email is config’d ok, Outlook can’t contact the mail servers. Loaded Norton AntiVirus, but it won’t update – can’t contact the server. It seems certain servers are being blocked. Removed ZoneLabs product from PC, found and removed Welchia worm. But still can’t contact these servers. Any ideas.
Would appreciate your assistance.

Regards,
Justin