I have an Exchange 2013 server that handles all email. I am using an Avaya IP Office Voicemail Pro to send voicemail to email. Server is rejecting addresses saying the address is invalid. Below is a clip of the log file.
501 5.1.7 Invalid addressQUIT
503 5.5.2 Need mail command
The email addresses are valid and are internal users.
Any suggestions as to how to fix?