Hi Steve63,

Sounds like you have to configure authentication (error "SMTP authentication failed").
I don's have my n800 with my now so I can't give you exect walkthru, but check your email-account information on PC (where sending mail is working) especially authentication settings (SSL, port 465 etc.) and copy those to n800's email settings - additional settings or something (I'm using Finnish interface)...

Good luck!