[iBook] "refused to allow a connection on port 5033"

[gooddog at interlync.com]

Folks;

I have been getting the following error message when trying to send  
mail. My mailbox on one account has next to it a sign with a triangle  
with an exclamation mark inside of it, referring to how I have been

"refused to allow a connection on port 5033"

I searched on google using "port 5033" and found references in  
French, but no where else.

My ISP says everything is set properly. I can email him, but I get  
this persistent message.

Any clues?

Thanks,

mark