Just as an update, this was indeed the problem. We no longer suffer with blank emails - Thank you! :)
They are/were Smacky, I've just changed that to infected only on your suggestion - will keep a close eye on it and see if it makes any difference,...
We're running an Exchange 2000 / Outlook 2003 setup in our company, and have up until now had no problems at all. NOD32 v2 has been serving us...
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