Third Party script cannot send email

[Ratatapa]

We have a Third Party company at work that has their own PC but need to use our mail server to send bulk emails

Problem is when they are trying to send email threw their program they receive this error

10/10/13 7:50:20 PM - -2147220977/The server rejected one or more recipient addresses. The server response was: 554 5.7.1 <unknown[X.X.X.X]>: Client host rejected: Access denied

the X.X.X.X is the PC IP adress

The ports are unlocked and if thye go on the website they can send email from it but not from their software

Their script is something cheap like that

[email protected]
[email protected]
authenticate=1
password=password
from=name
smtp=smtp
cdoport=587


halp me

[Arkanna]

Exchange?

[Ratatapa]

Nah Zimbra but found the problem

Third party not using tls encryption