We have been blacklisted by Spamcop and a few other spam blacklists... We are running Exchange 2003 that is patched and up to date... I did check to make sure we are not open relay and also after a previous blacklisting event, made sure that we are only sending NDRs from valid addresses. In the queues in Exchange system manager, there are many for wierd domain names ending in .de (postbank.de, lycos.de, etc)... I checked with our mxrecord host and they said that we arent showing as sending a lot of mail but our mail from unknown senders was high... I have enabled smtp authenticaion logging in exchange. I cant seem to pinpoint where this is coming from. Any help would be greatly appreciated!