Maybe fixed? Wiped partition cache. Uptime now over an hour with no reoccurrence of stuck "sending email" notification. Internet search "wipe partition cache" and your model to see the procedure. It's harmless and has fixed MANY problems for me over the years, especially after major updates
Hope that fixed your issues for you.
Still no success here, emailed Samsung again as others have also alluded to the same problem since the email update.
Hi, I cannot send emails either on Wifi or phone data. I am guessing after the update Samsung did not configure the outgoing email set up for Exchange Server accounts.