cannot send or receive email


I cannot send or receive email.

Here is the error message

The message could not be sent. The authentication setting might not be
correct for your outgoing e-mail [SMTP] server. For help solving this
problem, go to Help, search for "Troubleshoot Windows Mail", and read the
"I'm having problems sending e-mail" section. If you need help determining
the proper server settings, please contact your e-mail service provider.

The rejected e-mail address was 'ryan@xxxxxxxxxxxxx'. Subject 'wefww',
Account: '', Server: '', Protocol: SMTP,
Server Response: '452 <ryan@xxxxxxxxxxxxx> Mailbox size limit exceeded',
Port: 25, Secure(SSL): No, Server Error: 452, Error Number: 0x800CCC79

Please help I need this email to run my business.