Unable to reply to group messages initiated through Microsoft Outlook.

My office uses group messaging initiated through Microsoft Office to send information to employees' phones. It starts as an email, gets converted to text message by the service provider and sent to the phone. All other personnel in my office can receive messages and send responses with no issues. My iPhone 6S can receive messages, but when I reply the sender never receives the response. I am the only iPhone 6S T-Mobile user. Other T-Mobile users have not issues. Is there a setting in messages that could be affecting my ability to respond?