In a word Yes.
Scanning outbound email: one helps stop the spread of infection; two can give you an indication of an undetected infection that turns your system in to a Spam machine sending out multiple emails that without outbound checks you wouldn't even be aware of and risk being banned by your ISP for spamming; three you should try to resolve the problem rather than ignore the symptom and increase the risk to others.
All I can suggest relating to your other thread is to check you are connected before sending email.
Do you still have OE or another email program?
If so you could try to replicate this problem by trying to send email whilst not connected and see if this too dissapears, which I feel it won't. I use OE and if I try to send email whilst offline it ask if I want to connect.
The problem as far I can see (from briefly reading your thread) is, one you don't get this off-line warning from PMAIL if you try to send email when not connected, two once sent PMAIL assumes that's it, it has been send and deletes the entry and doesn't wait for a received response from the email server, which it won't get because you are off-line. Does it save a copy of the email in the sent items folder? - if so you can surely resend that?
So to sumarise, to kill outbound scans to overcome something that only happend when you forget to check you are connected seems overkill, yes if this was happening every time or there were issues when you were on-line.
