thanks so much to all for the great suggestions.........i'm going to investigate these possibilities........oddly, one of my scripts from the same domain, using the same From: address as on the script that is failing works just fine(!?!?)....haven't sorted out what's different - looks identical. they both have subject headers, so that's not it....ugh!

but, nevermind - i do appreciate the assistance from your most-knowledgeable monks!