If anyone is interested, I documented a fairly easy way to prevent third party SMTP relaying with MULTINET 4.1 on a VMS 5 MicroVAX. http://vintagecomputer.net/browse_thread.cfm?id=708 I did cheat a little...I set up an email alias on my modern mail server to forward messages to a single email address on the VAX. This was necessary because otherwise I'd have to have added the mail host ID of every mail server permitted to send email to users on the VAX. Also, I will have to create an alias on the modern mail server for every VAX user who wanted to get mail. I agree ultimately that MULTINET email is too limited, but for my purposes I am satisfied. It's just for the learning experience. Bill