Abuse.net mail header problem

[Dr. Jeffrey Race]

On Sat, 07 Oct 2000 11:36:35 -0700 (PDT), Kris Sorem Sr wrote:
>Did you carbon copy the message to yourself? If so, check the /Message-ID/
>line in the message header. If correct, the problem is with the receiving
>server. If not, the problem is with your ISP.

None of my outgoing mail contains a Message-ID field.  What RFC or
other standard specifies this is required for a wellformed message?

Jeffrey Race