I an not having any luck on this.
I tried Thunderbird, and liked parts of it, but it would not let me choose my mail recipients in a way that works for me, so I’m back to OE. I wanted rid of it because it insisted on deleting emails that I wanted. I checked for any content that would trigger my message rules, but found none. It mostly happened with one person, so I just kept watch. Now it’s happening with several, and there is still no trigger discernable.
Halp!
And, TIA!