Hi Mark, by blank I'm guessing you mean no email address? If this is what you mean then yes there's no blocking them. This is where it's get technical and very time consuming. Microsoft advice to this is to use the Manage Rules section. I have done all this, found the message source and made a rule to block that address and still nothing works because the spammers just keep changing their sender address. How to do this is click and highlight but don't open the spam email, right click on this particular email and scroll down the list to the word View, hold your cursor on this and to the right is 3 selections, click on View Message Source. This is where it gets really technical because what it opens up is lots of computer jargon, interesting but beyond my comfort zone lol. Scroll down slowly until you see your email address and under this is the message address. This is the address you can copy and paste into a new rule but no matter how many times you do this the spammer will find another address to use. This is where Microsoft is failing badly. It should be stopping all this before it even gets to our Outlook server.