Longtime listener, first time poster (on this topic anyway) _IF_ it's possible to reliably (and easily) identify the MailWasher bounces, why not just use that to identify customers using it, and block them from your mail server for a while (Hell, even disable their account perhaps) BUT, and this is the important bit, Send an email to the MW developers telling them that as an ISP you are blocking customers that use their software in this way. Suggest that users of their software will find their Intarwebthingy disabled. Sure the developers may not like taking out neat features, but they probably won't like fielding calls from users who get their net killed because of their product either. Cheers - N. NOTICE: This message contains privileged and confidential information intended only for the use of the addressee named above. If you are not the intended recipient of this message you are hereby notified that you must not disseminate, copy or take any action in reliance on it. If you have received this message in error please notify Allied Telesyn Research Ltd immediately. Any views expressed in this message are those of the individual sender, except where the sender has the authority to issue and specifically states them to be the views of Allied Telesyn Research.