feat: apply SMTP limits to connections

mail/mail/doctype/mail_settings/mail_settings.json

@@ -33,6 +33,7 @@
   "column_break_9j6r",
   "smtp_session_duration",
   "smtp_inactivity_timeout",
+  "smtp_cleanup_interval",
   "spamassassin_tab",
   "section_break_hgqa",
   "enable_spamd",
@@ -354,12 +355,21 @@
    "fieldname": "limit_outbound_message_section",
    "fieldtype": "Section Break",
    "label": "Message"
+  },
+  {
+   "default": "60",
+   "description": "The interval for cleaning up stale connections.",
+   "fieldname": "smtp_cleanup_interval",
+   "fieldtype": "Int",
+   "label": "Cleanup Interval (Seconds)",
+   "non_negative": 1,
+   "reqd": 1
   }
  ],
  "index_web_pages_for_search": 1,
  "issingle": 1,
  "links": [],
- "modified": "2025-01-09 12:17:12.266240",
+ "modified": "2025-01-09 12:32:06.490297",
  "modified_by": "Administrator",
  "module": "Mail",
  "name": "Mail Settings",

mail/mail/doctype/mail_settings/mail_settings.py

@@ -15,6 +15,7 @@ def validate(self) -> None:
 		self.validate_spf_host()
 
 	def on_update(self) -> None:
+		frappe.cache.delete_value("smtp_limits")
 		frappe.cache.delete_value("root_domain_name")
 
 		if self.has_value_changed("root_domain_name"):

mail/smtp.py

@@ -5,6 +5,8 @@
 from smtplib import SMTP, SMTP_SSL, SMTPServerDisconnected
 from threading import Lock, Thread
 
+from mail.utils.cache import get_smtp_limits
+
 
 class SMTPConnectionLimitError(Exception):
 	pass
@@ -21,12 +23,12 @@ def __init__(
 		use_tls: bool,
 		inactivity_timeout: int,
 		session_duration: int,
-		max_emails: int,
+		max_messages: int,
 	) -> None:
 		self.__created_at = time.time()
 		self.__inactivity_timeout = inactivity_timeout
 		self.__session_duration = session_duration
-		self.__max_emails = max_emails
+		self.__max_messages = max_messages
 		self.__email_count = 0
 
 		self.session = self.__create_connection(host, port, username, password, use_ssl, use_tls)
@@ -59,7 +61,7 @@ def is_valid(self) -> bool:
 		expired = (
 			current_time - self.last_used > self.__inactivity_timeout
 			or current_time - self.__created_at > self.__session_duration
-			or self.__email_count >= self.__max_emails
+			or self.__email_count >= self.__max_messages
 		)
 		return not expired and self.is_active()
 
@@ -87,14 +89,19 @@ def __new__(cls, *args, **kwargs) -> "SMTPConnectionPool":
 				cls._instance._running = False
 		return cls._instance
 
-	def __init__(self, max_connections: int) -> None:
+	def __init__(self) -> None:
 		if hasattr(self, "_initialized"):
 			return
 
-		self.max_connections = max_connections
+		smtp_limits = get_smtp_limits()
+		self.max_connections = smtp_limits["max_connections"]
+		self.max_messages = smtp_limits["max_messages"]
+		self.session_duration = smtp_limits["session_duration"]
+		self.inactivity_timeout = smtp_limits["inactivity_timeout"]
+		self.cleanup_interval = smtp_limits["cleanup_interval"]
+
 		self._initialized = True
 		self._running = True
-		self._cleanup_interval = 60
 		self._cleanup_thread = None
 		self._initialize_cleanup_thread()
 
@@ -106,9 +113,6 @@ def get_connection(
 		password: str,
 		use_ssl: bool,
 		use_tls: bool,
-		inactivity_timeout: int,
-		session_duration: int,
-		max_emails: int,
 	) -> "SMTPConnection":
 		key = (host, port, username)
 		with self._pool_lock:
@@ -136,9 +140,9 @@ def get_connection(
 					password,
 					use_ssl,
 					use_tls,
-					inactivity_timeout,
-					session_duration,
-					max_emails,
+					self.inactivity_timeout,
+					self.session_duration,
+					self.max_messages,
 				)
 
 			raise SMTPConnectionLimitError(
@@ -173,7 +177,7 @@ def _initialize_cleanup_thread(self) -> None:
 
 	def _cleanup_stale_connections(self) -> None:
 		while self._running:
-			time.sleep(self._cleanup_interval)
+			time.sleep(self.cleanup_interval)
 			with self._pool_lock:
 				for key, pool in self._pools.items():
 					valid_connections = Queue(self.max_connections)
@@ -208,21 +212,14 @@ def __init__(
 		password: str,
 		use_ssl: bool = False,
 		use_tls: bool = False,
-		inactivity_timeout: int = 300,
-		session_duration: int = 600,
-		max_emails: int = 10,
-		max_connections: int = 5,
 	) -> None:
-		self._pool = SMTPConnectionPool(max_connections)
+		self._pool = SMTPConnectionPool()
 		self._host = host
 		self._port = port
 		self._username = username
 		self._password = password
 		self._use_ssl = use_ssl
 		self._use_tls = use_tls
-		self._inactivity_timeout = inactivity_timeout
-		self._session_duration = session_duration
-		self._max_emails = max_emails
 		self._connection = None
 
 	def __enter__(self) -> SMTP | SMTP_SSL:
@@ -233,9 +230,6 @@ def __enter__(self) -> SMTP | SMTP_SSL:
 			self._password,
 			self._use_ssl,
 			self._use_tls,
-			self._inactivity_timeout,
-			self._session_duration,
-			self._max_emails,
 		)
 		return self._connection.session
 
@@ -255,15 +249,9 @@ def smtp_server(
 	password: str,
 	use_ssl: bool = False,
 	use_tls: bool = False,
-	inactivity_timeout: int = 300,
-	session_duration: int = 600,
-	max_emails: int = 10,
-	max_connections: int = 5,
 ) -> Generator[type[SMTP] | type[SMTP_SSL], None, None]:
-	_pool = SMTPConnectionPool(max_connections)
-	_connection: SMTPConnection = _pool.get_connection(
-		host, port, username, password, use_ssl, use_tls, inactivity_timeout, session_duration, max_emails
-	)
+	_pool = SMTPConnectionPool()
+	_connection: SMTPConnection = _pool.get_connection(host, port, username, password, use_ssl, use_tls)
 
 	try:
 		yield _connection.session

mail/utils/cache.py

@@ -11,6 +11,20 @@ def generator() -> str | None:
 	return frappe.cache.get_value("root_domain_name", generator)
 
 
+def get_smtp_limits() -> dict:
+	def generator() -> dict:
+		mail_settings = frappe.get_cached_doc("Mail Settings")
+		return {
+			"max_connections": mail_settings.smtp_max_connections,
+			"max_messages": mail_settings.smtp_max_messages,
+			"session_duration": mail_settings.smtp_session_duration,
+			"inactivity_timeout": mail_settings.smtp_inactivity_timeout,
+			"cleanup_interval": mail_settings.smtp_cleanup_interval,
+		}
+
+	return frappe.cache.get_value("smtp_limits", generator)
+
+
 def get_postmaster_for_domain(domain_name: str) -> str:
 	"""Returns the postmaster for the domain."""