OTRS will not send respond email

[PCS David]

We are new to OTRS. OTRS is installed on a windows 2003 box. Another box has exchange 2007. Both on the same subnet.
Apparently OTRS is having troubles authenticating with our exchange 2007 to send out a response.
OTRS is downloading new emailed tickets, but does not send a response.
Is there any additional configuration steps that need to be made on the exchange server to allow OTRS to send email through it?
We are using pretty much out of the box exchange settings

[crythias]

You should have an error message of some sort, ...

[PCS David]

[Sun Mar 13 12:12:21 2011][Error][Kernel::System::Email::SMTP::Send][145] Can't send to 'xxx.xxx@gmail.com': 5505.7.1 Unable to relay! Enable Net::SMTP debug for more info!
[Sun Mar 13 12:12:21 2011][Info][Kernel::System::Email::Send] Error sending message
[Sun Mar 13 12:12:21 2011][Error][Kernel::System::Ticket::Article::ArticleSend][2042] Impossible to send message to: xxxx xxx <xxxx.xxx@gmail.com>

[crythias]

that's a problem with Exchange not allowing relay.

[PCS David]

Thanks
Problem solved with Exchange