... I don't think you need both of them plus the Script Blocker of avast!
Technical,I don't use both. You misunderstand. I use Script Sentry with my Avast Home in my W98 since Avast Home does not have script blocking.
My Avast Pro sits happily in my XP computer with its' internal script blocking.
Ok Ok.....Script Defender is a bit better than Defender. However, I believe that Sentry is still is supported. Defender is not.

Walker,
As I understand the problem, you have Pegasus sending mail to your computer at which time it is redirected to local host 127.0.0.1 so that Avast can scan first. This link is not working at all times. Am I correct here?
I asssume that when you "remove" the local host path, you set the server address to that of Pegasus and all works fine.
Can we try a simple test? If I remember, you have Avast Pro...Yes?
Really doesn't matter. You will be sending email to yourself. Go into Settings and uncheck Scan outgoing mail so that Avast will not scan it.
Then, try sending mail. If this is successful, then reverse the permissions (outgoing..scan, incoming..no scan). Try again.
Can you check your Windows Event Viewer log (System and Application) to see if anything shows up as an error or conflict message? I do not think anything will show in the Avast log since it is waiting to scan email that it never sees. Understand?
We will have to do a bit of old fashioned troubleshooting here before we try drastic stuff like reinstallations. This may be simplistic but have you tried to reinstall Avast or Pegasus?
Do you agree? It will be my pleasure to try and find a solution for you.
I will try to get the attention of a Moderator or Avast Team Member. I can't offer an explanation as to why Alwil Support does not answer your email.
techie