Question : Exchange 2010 Send-As permissions do not stay applied

I have an Exchange 2010 server, running on Windows 2008 R2. To make an email sending program work in one of my internal applications, I created an account, and then set Send-As permissions for that account on about 15 user mailboxes. This worked fine for a while, but then the Send-As permission for that account goes away on those mailboxes after some period of time and breaks the program. This error is returned:
"The server response was 550 5.7.1 Client does not have permissions to send as this sender"

If I set the permission again, it will work for a while and then disappear from the accounts. I am doing this through the management console, by going to Recipient Configuration\Mailbox

Right-click the user and choose Manage Send-As permissions. Then I click Add and choose the new account I created and click the Manage button to apply the change.  

I am not an Exchange expert by any measure, so any help would be greatly appreciated.

Answer : Exchange 2010 Send-As permissions do not stay applied

What about something like this?

dsacls "cn=AdminSDHolder,cn=system,dc=domain,dc=example,dc=com" /G "domain\ApplicationAdminAcct:CA;Send As"