Allow to have several postfix hosts

app/mail_sender.py

@@ -100,6 +100,7 @@ class MailSender:
     def __init__(self):
         self._pool: Optional[ThreadPoolExecutor] = None
         self._store_emails = False
+        self._randomize_smtp_hosts = True
         self._emails_sent: List[SendRequest] = []
 
     def store_emails_instead_of_sending(self, store_emails: bool = True):
@@ -146,7 +147,8 @@ class MailSender:
 
     def _send_to_smtp(self, send_request: SendRequest, retries: int) -> bool:
         servers_to_try = config.POSTFIX_SERVERS.copy()
-        random.shuffle(servers_to_try)
+        if self._randomize_smtp_hosts:
+            random.shuffle(servers_to_try)
         if config.POSTFIX_BACKUP_SERVERS:
             servers_to_try.extend(config.POSTFIX_BACKUP_SERVERS)
         servers_tried = 0
@@ -177,22 +179,22 @@ class MailSender:
             return self._send_to_smtp(send_request, retries - 1)
         else:
             if send_request.ignore_smtp_errors:
-                LOG.e("Ignore smtp error")
+                LOG.w("Ignore smtp error and skip saving to fs email")
                 return False
-            LOG.e(
-                f"Could not send message to smtp server {config.POSTFIX_SERVERS}:{config.POSTFIX_PORT}"
-            )
             if config.SAVE_UNSENT_DIR:
                 send_request.save_request_to_unsent_dir()
             return False
 
     def __send_to_server(self, server_host: str, send_request: SendRequest):
         start = time.time()
-        with SMTP(
-            server_host,
-            config.POSTFIX_PORT,
-            timeout=config.POSTFIX_TIMEOUT,
-        ) as smtp:
+        server_split = server_host.split(":")
+        if len(server_split) == 1:
+            server_host = server_split[0]
+            server_port = config.POSTFIX_PORT
+        else:
+            server_host = server_split[0]
+            server_port = server_split[1]
+        with SMTP(server_host, server_port, timeout=config.POSTFIX_TIMEOUT) as smtp:
             if config.POSTFIX_SUBMISSION_TLS:
                 smtp.starttls()
 
@@ -219,7 +221,7 @@ class MailSender:
                 send_request.mail_options,
                 send_request.rcpt_options,
             )
-            return True
+        return True
 
 
 mail_sender = MailSender()

tests/test_mail_sender.py

@@ -109,6 +109,7 @@ def test_mail_sender_save_unsent_to_disk(server_fn):
     config.POSTFIX_SERVERS = ["localhost"]
     config.NOT_SEND_EMAIL = False
     config.POSTFIX_SUBMISSION_TLS = False
+    config.POSTFIX_TIMEOUT = 6000
     config.POSTFIX_PORT = server_fn()
     try:
         with tempfile.TemporaryDirectory() as temp_dir:
@@ -126,6 +127,22 @@ def test_mail_sender_save_unsent_to_disk(server_fn):
         config.NOT_SEND_EMAIL = True
 
 
+def test_mail_sender_try_several_servers():
+    port_closed = closed_dummy_server()
+    port_ok = smtp_response_server("250 Ok")()
+    original_postfix_server = config.POSTFIX_SERVERS
+    config.POSTFIX_SERVERS = [f"localhost:{port_closed}", f"localhost:{port_ok}"]
+    config.NOT_SEND_EMAIL = False
+    config.POSTFIX_SUBMISSION_TLS = False
+    send_request = create_dummy_send_request()
+    mail_sender._randomize_smtp_hosts = False
+    try:
+        assert mail_sender.send(send_request, 0)
+    finally:
+        config.POSTFIX_SERVERS = original_postfix_server
+        config.NOT_SEND_EMAIL = True
+
+
 @mail_sender.store_emails_test_decorator
 def test_send_unsent_email_from_fs():
     original_postfix_server = config.POSTFIX_SERVERS