Hi,

after provided more tests were found that (in my case) reason and solution (I saw that behaviour from August 2020 to till now)

Description of workaround and provided steps
- Openned pdf document in Adobe Acrobat Reader DC (still updated version, recently 2020.013.20074),
- In Adobe File/Share file/Outlook message (Office 365 still update, recently version 16.0.13530.20132, 64bit),
- Then is automatically opened Outlook new message,
- message is fulfilled with the data and addresses, then click on send,
- Outlook and Adobe are still opened,

• standard work in both and next application (time to time (hapened not always, olny sporadicaly), don´t know the trigger of issue, but Outlook is seems like freezen (no any reaction to command by mouse or keyboard) - then when you close (standard close of application, not kill the process) Adobe Acrobat Reader DC you can continue with work in Outlook, no further action are required).

Maybe you can find the code bug and reapair it (I will be happy if you can share your feedback).
Thank you.