Obtain help on using the mail server.
HELP
The HELP command returns a description of the commands recognized by the mail server.
%MAILSERV-F-HLPNOTAVA, Help for server is presently unavailable
No help information is currently available. This may or may not be a temporary condition.
%MAILSERV-W-MAXPARM, too many parameters
You supplied a parameter after the HELP command. The HELP command does not accept any parameters (e.g., does not take a "topic" parameter).