Simple New Mail Notification
RFC 4146

Received changes through RFC Editor sync (changed abstract to 'This memo documents a long-standing technique, supported by a large number of mail servers, which allows users to be notified of new mail. In addition to server support, there are a number of clients that support this, ranging from full email clients to specialized clients whose only purpose is to receive new mail notifications and alert a mail client.

In brief, the server sends the string "nm_notifyuser" CRLF to the finger port on the IP address (either configured or last used) of the user who has received new mail. This memo provides information for the Internet community.')