diff -r 8f8fce2dd594 -r b0253377e170 mercurial/mail.py
--- a/mercurial/mail.py	Thu Mar 11 17:02:28 2021 -0500
+++ b/mercurial/mail.py	Thu Mar 11 17:04:58 2021 -0500
@@ -165,7 +165,7 @@
         try:
             s.login(username, password)
         except smtplib.SMTPException as inst:
-            raise error.Abort(inst)
+            raise error.Abort(stringutil.forcebytestr(inst))
 
     def send(sender, recipients, msg):
         try: