Hello Reginab,
We're sorry for the trouble you had with Adobe Reader, try adding a different email account and see if this issue is reproducible?
Remove Adobe Reader using Acrobat cleaner tool Download Adobe Reader and Acrobat Cleaner Tool - Adobe Labs
Reboot the machine and install the Adobe Reader version 19.008.20071 from Adobe - Adobe Acrobat Reader DC Distribution
Then from help>check for updates, install the latest patch 19.008.20074, reboot the machine again and check.https://get.adobe.com/reader/enterprise/
Is it possible to post a screenshot of the default mail settings window? To post a screenshot, refer to https://forums.adobe.com/docs/DOC-7043#jive_content_id_How_do_I_attach_a_screenshot
Try adding the mail account from Adobe Preferences settings Edit>Preferences>Email accounts and check.
Let us know how it goes and share your observation.
Thanks,
Anand Sri.