[WP] (csbackntfy): only use login mechanism if username is set

csbackntfy.py

@@ -329,8 +329,7 @@ def main(argv=None):
 
         if 0 == len(host):
           raise Usage("Hostname missing.", eCodes.GLOBAL_UsageError)
-        if 0 == len(username):
-          raise Usage("Username missing.", eCodes.GLOBAL_UsageError)
+        if 0 != len(username):
           if 0 == len(password):
             raise Usage("Password missing.", eCodes.GLOBAL_UsageError)
         if -1 == port:
@@ -400,6 +399,7 @@ def main(argv=None):
           if useTLS:
             session.starttls()
             session.ehlo()
+          if 0 != len(username):
             session.login(username, password)
           session.sendmail(sender, receivers, mail.as_string())
         except smtplib.SMTPRecipientsRefused: