An error occurred while sending mail

I have Adobe Pro DC. I am unable to Send file as Attachment. I can confirm that I can attach files in Outlook 2016. Below is the error message. I saw some people had simlar problems. I did the following: 1)Repiared Adobe 2) followed the 'How to use the Emial Icon to send a PDF directly as E-mail attachment." https://helpx.adobe.com/acrobat/kb/send-email-attachment.html 3)I changed the defualt app setting to Outlook.