Add config option to disable SMTP auth for basic postfix setup (#314)

Sometimes it is useful to disable SMTP authentication for sending emails. For example, if someone is using a local postfix server, the default install doesn't require/enable auth.

When this new config option is set to enable_smtp_auth: false, the username_smtp and password_smtp config options are ignored.

config-example.yaml

@@ -79,6 +79,7 @@ notifier:
       recipient: '[email protected]'
       username_smtp: 'username'
       password_smtp: 'password'
+      enable_smtp_auth: true
       host: 'smtp.example.com'
       port: 587
   script:

src/notifier/smtp_notifier.py

@@ -24,6 +24,7 @@ def __init__(self, title_prefix: str, config: dict):
             self.password_smtp = credentials["password_smtp"]
             self.host = credentials["host"]
             self.port = credentials["port"]
+            self.enable_smtp_auth = credentials.get("enable_smtp_auth", True)
 
         except KeyError as key:
             logging.error(f"Invalid config.yaml. Missing key: {key}")
@@ -57,7 +58,8 @@ def send_events_to_user(self, events: List[Event]) -> bool:
                     server.starttls()
                     # stmplib docs recommend calling ehlo() before & after starttls()
                     server.ehlo()
-                    server.login(self.username_smtp, self.password_smtp)
+                    if self.enable_smtp_auth:
+                        server.login(self.username_smtp, self.password_smtp)
                     server.sendmail(self.sender, self.recipient, msg.as_string())
                     server.quit()
                 # Display an error message if something goes wrong.