Question : Client does not have permissions to send as this sender

Hello,
I have installed Exchange Server 2007 on my server, connection with outlook and webmail works perfectly, I can send and receive mail without a problem.

However, I installed a mailing program called Interspire SendStudio, so I can send newsletters to my subscribers. When I test the SMTP connection I get the following error:
5.7.1 Client does not have permissions to send as this sender

I have verified the SMTP settings and they are correct. Port I use is 25, username is created and I can access it using webmail (OWA) or outlook without a problem.

Answer : Client does not have permissions to send as this sender

that is the account you need to configure with 'send as' rights to the account you are 'sending as'

you do that in ADUC

navigate to the account you are sending as
righ-click - properties
security - advanced
add - the account your program is configured to use
scroll to the bottom - check 'Send As'
OK all the way out

now the error should go away