503 This server needs authentication

[adrian]

The message could not be sent because one of the
recipients was rejected by the server. The rejected e-
mail address was '(e-mail address removed)'. Subject 'message
from express', Account: 'mail.pontesquash.com',
Server: 'mail.pontesquash.com', Protocol: SMTP, Server
Response: '503 This mail server requires authentication.
Please check your mail client settings.', Port: 25, Secure
(SSL): No, Server Error: 503, Error Number: 0x800CCC79

 

[neo [mvp outlook]]

You should contact the help desk of pontesquash.com because they are asking
the sender (you) to do one of the following.

1) logon to the server in order to send a message (use the same credentials
as your POP3/IMAP account)

or

2) Check your e-mail and then send the message. (Outlook sends and then
receives while most internet e-mail programs do the reverse.)

Since you didn't mention which version of Outlook you are using, it will be
difficult to let you know which to try.