Quit Acrobat or Reader if it's already running.
Outlook and Acrobat or Reader may freeze on consecutive attempts to use Send Mail
Consecutive attempts to send a PDF as an attachment from within Acrobat or Reader may result in both Acrobat/Reader and Outlook freeze/crash.
Affected products on Windows: Microsoft Office 14 through Office 365 and Acrobat, Acrobat 2017, Acrobat 2015, Acrobat Reader, Acrobat Reader 2017, or Acrobat Reader 2015.
Solution: Apply the registry to resolve the problem
A registry protected workaround is available to fix this problem. Download the registry file and apply the changes as suggested below.
Download the zip file - click Get file.
Unzip or extract the downloaded file to the desktop. Right-click the file (Adobe.reg) and choose Merge.