Send Button Greyed Out For New Messages

This morning, I am not able to send new emails form outlook 365 on a Mac.  I can type a message and put in a recipient but the Send button stays greyed out.  I have quit and relaunched Outlook and am still having the issue.  Any advice on how to resolve?  

I am able to create and send through the Outlook app on my phone and I am able to reply and forward form my computer.  I just cannot create new messages form my computer.