Mail not sending

[skinner]

YaBB SE Version: 1.5.4
PHP Version: 4.3.2
MySQL Version: 4.0.x
Server Platform: Windows
Link to Forum:

Problem Description:
  i am having problems sending mail from yabb se i have been using the perl version of yabb for ages and now i have decided to change over to the se edition, i have found i am having problems sending mail i have tried 2 diffrent smtp servers and both do the same. can anybody shed any light on this for me ?

oh yeah here is the message that is reported

2: mail(): SMTP server response: 550 5.7.1 Unable to relay for

thanks in advance

Mark

[[Unknown]]

Make sure you have set your email and password correctly in Installed 'Mods' Settings and Options.

-[Unknown]

[skinner]

Yup have tried that too but i get another error then  

Ran into problems sending Mail. Error: 503 you are already authenticated.

[[Unknown]]

Talk to your host... may be a buggy mail server.

-[Unknown]