Thank you for that, Matt. Unfortunately, I had no more luck with that approach than what I had been using, but I certainly had not been aware of the possibility of making those variables into properties.
The use (and desire to expose) the global variables were one approach that has now been superseded. By tracking what's been written (by populating an array) and checking that array (rather than the SharePoint list), I'm able to achieve my goal. For whatever reason, it appears that calling findExisting for each email message is "too much," and by saving the call for only when the array shows an existing item, the system appears to be able to keep up.
It's quite possible, too, that our environment (of IE7 and Windows XP) is contributing to odd behavior. I had earlier written of a phenomenon (stack overflow) that happens only within that environment and not, say, using IE8 with MOSS.
