What does this mean ?

"An unknown error has occurred. Subject ' Lemon
Meringue', Account: 'nn_Earthlink', Server:
'smtpauth.earthlink.net', Protocol: SMTP, Server
Response: '550 Your message does not conform to
RFC2822 standard', Port: 587, Secure(SSL): No,
Server Error: 550, Error Number: 0x800CCC69"

I was forwarding on one of the funny e-mails I
received. Never used to get an error response but
now I seem to be getting this
error response more frequently.

Help !