AVG email problems

I have AVG 7 and I am using OE for my email. I have two accounts which run
fine, however my new account will not work with AVG at all for me.
I set it up to run in outlook express as usual and it will send and receive
fine, however when I import its details into AVG it will no longer receive
mail, and all mail I send is returned as undelivered.
The new account requires authentication, which my old ones do, however this
one has auth. infront of the smtp.xxxx.xxxx (hence it is auth.smtp.xxxx.xxx)
Is this why AVG is stopping it working? If so will missing out the auth.
work, or is there another way around this problem?

Thanks