According to your list header, you don't have Send= Editor,Hold,Confirm . Not having that little ",Confirm" on the end--as documented--can leave you wide open to loops or spoofs. We have been recommending for some time that announce-only lists be set to Send= Editor,Hold,Confirm . This forces mail sent even from an Editor to have to be confirmed by that editor before it can be distributed. It's a little annoying but in the end it can save you having this problem. It looks to me like this message actually looped back from a user at HEALTHGATE.COM . Since it had a From: line with your address, it went right through. If you'd had ",Confirm" set on the Send= keyword it would have come to you for approval first. FYI this is a really common occurance with remote hosts that use the Microsoft SMTPSVC MTA, which probably isn't 100% RFC compliant. I suspect the Microsoft product rewrites the RCPT TO: lines in the envelope, but it's hard to say since we don't use it. Nathan