I started having problems some weeks back with Xtra mailboxes not receiving mail from a number of lists that we send. After a bit of troubleshooting our end, a query to Xtra helpdesk revealed that they now filter emails that have a blank Mail From, To or Subject field (our lists have never had a from address and our email server appears to not have the facility to add one, which kinda makes it my problem but ...). Xtra said: "We have implemented a rule on our Xtra Email Servers requiring at a minimum of a From email address, To email address, and a subject to be displayed to prevent this form of Spam. If all of these are enterred into the email this will ensure continued delivery of the automated emails. The Anti-Spam filter works by checking the content and style of email content. These blank emails have hidden content in the body that appears legitimate to the Anti-Spam filter and are passed." Not sure if this is news or not, but I hadn't seen anything publicised re this change. My understanding was that blank "from" fields are valid, so filtering this type of email may break other things such as read receipts. Has this been a problem for anyone else out there? Dave