Adobe Reader 2016 For Mac
Have you reinstalled or done an Adobe repair?
Have you tried checking out the send to or mail to from other programs to see if it is a Microsoft Mail link that is broken?
Adobe Acrobat Reader DC is the free, trusted standard for viewing, printing, and annotating PDFs. And now, it's connected to Adobe Document Cloud - so it's easier than ever to work with PDFs on computers and mobile devices. Adobe Reader 2017 for Mac is the safest variation Adobe have launched. This is generally due the brand new Protected Mode which tons likely harmful things and standard in a sandboxed area, segregated from the rest of your device.
Ok, checked a thread from Adobe...Here is the link.
Read the post from Mike M
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Adobe Reader 2016 For Mac Download
I tried this and my Send to was grayed out. I went through the process to add an email account and noted that Outlook email was listed. I still went ahead and added my own outlook email (not sure if it was accurate info regarding SMTP or IMAP).
Adobe Reader 2016 For Mac 10.6.8 Free Download
When I went to send to email the second time, it wasn't grayed out but rather than using the email I created, I used the Outlook mail link and sent it and verified I did receive it as well.