I have been using avast successfully for quite a while until the latest update. After the update I could no longer send e-mail, every thing I tried got a error 550 not a local host not a gateway.
I checked the smtp and pop settings in Eudora and they hadn’t changed from what they had been previous to the update. I could receive e-mail, but not send.
Have you tried to run the Mail Protection wizard again?
Shutdown Endura first, windows Start>All Programs>avast!>Mail Protection Wizard. This assumes that you are using XP and you previously were able to set endura up with M.P.W. or did you have to set it up manually if so you will have to follow these steps again.
Have your avast4.ini settings (…\avast\data\avast4.ini) changed recently (check the date last modified in properties)?
This error usually means that you need to turn on authentication for outgoing mail.