Closes #25411: Merged fix from 3.5.

diff --cc Lib/logging/handlers.py
Simple merge

diff --cc Misc/NEWS
index 7d2c79f85bd3650b2e7061b28cb99c8a17553c64,71009af0a348016eb56d26462e50dba6b7b72efa..0cb9c183b3ed67f235092df326298b0570019cc0
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -63,8 -45,9 +63,11 @@@ Core and Builtin
  Library
  -------
  
+ - Issue #25411: Improved Unicode support in SMTPHandler through better use of
+   the email package. Thanks to user simon04 for the patch.
+ 
 +- Move the imp module  from a PendingDeprecationWarning to DeprecationWarning.
 +
  - Issue #25407: Remove mentions of the formatter module being removed in
    Python 3.6.