I installed Avast 4 - and much to my surprise I found the defaults were
These hardly seem to me to be ‘logical’ defaults for an ANTI-VIRUS program.
Anyone else notice this? (Hope so 
)
It’s certainly not the default behavior.
What operating system do you use? Do you use any special proxies? Do you use secure (SSL/TLS) connections to your mailserver?
Using XP Pro - there really is minimum stuff on the computer.
It is stripped down as far as it can go as only has 6GB hard drive capacity - even no Office - just basically used for internet connection - and audio/video from MLB
Absolutely NOTHING special or exotic. Simple single unit - using ADSL.
I have only semi-intelligent observor status 
with most of the terms and tricks of the computer trade - and so really don’t try anything unless have been advised to (otherwise catch the ire of an impatient son who then says he has to ‘fix’ everything)
Can you post a list of your Thunderbird extensions?
Did you use any other antivirus in this computer (even in the past)? Which one? How did you uninstall it?
Only using standard extensions
Here’s what may be the reason - was going to add in above reply that had been using Norton AV - but what of course is more than incidental is that I have been ready to uninstall it - but so far did not - frankly just simply scared to - because it is still warning of ‘high risk’ intrusions - and as everything seems to be working (I changed the defaults that I am ‘complaining’ about) - I am dubious to change what is working.
I now expect a flood of ‘you dumb idiot - how can you be running 2 AV’s concurrently’ etc. :
For sure it won’t work. You need to remove Norton.