feat: allow pass hostname in docker env

api/.env.example

@@ -417,6 +417,8 @@ SMTP_USERNAME=123
 SMTP_PASSWORD=abc
 SMTP_USE_TLS=true
 SMTP_OPPORTUNISTIC_TLS=false
+# Optional: override the local hostname used for SMTP HELO/EHLO
+SMTP_LOCAL_HOSTNAME=
 # Sendgid configuration
 SENDGRID_API_KEY=
 # Sentry configuration
@@ -713,3 +715,4 @@ ANNOTATION_IMPORT_MAX_CONCURRENT=5
 SANDBOX_EXPIRED_RECORDS_CLEAN_GRACEFUL_PERIOD=21
 SANDBOX_EXPIRED_RECORDS_CLEAN_BATCH_SIZE=1000
 SANDBOX_EXPIRED_RECORDS_RETENTION_DAYS=30
+

api/configs/feature/__init__.py

@@ -949,6 +949,12 @@ class MailConfig(BaseSettings):
         default=False,
     )
 
+    SMTP_LOCAL_HOSTNAME: str | None = Field(
+        description="Override the local hostname used in SMTP HELO/EHLO. "
+        "Useful behind NAT or when the default hostname causes rejections.",
+        default=None,
+    )
+
     EMAIL_SEND_IP_LIMIT_PER_MINUTE: PositiveInt = Field(
         description="Maximum number of emails allowed to be sent from the same IP address in a minute",
         default=50,

api/libs/smtp.py

@@ -3,6 +3,8 @@
 from email.mime.multipart import MIMEMultipart
 from email.mime.text import MIMEText
 
+from configs import dify_config
+
 logger = logging.getLogger(__name__)
 
 
@@ -19,20 +21,19 @@ def __init__(
         self.opportunistic_tls = opportunistic_tls
 
     def send(self, mail: dict):
-        smtp = None
+        smtp: smtplib.SMTP | None = None
+        local_host = dify_config.SMTP_LOCAL_HOSTNAME or ""
         try:
-            if self.use_tls:
-                if self.opportunistic_tls:
-                    smtp = smtplib.SMTP(self.server, self.port, timeout=10)
-                    # Send EHLO command with the HELO domain name as the server address
-                    smtp.ehlo(self.server)
-                    smtp.starttls()
-                    # Resend EHLO command to identify the TLS session
-                    smtp.ehlo(self.server)
-                else:
-                    smtp = smtplib.SMTP_SSL(self.server, self.port, timeout=10)
-            else:
-                smtp = smtplib.SMTP(self.server, self.port, timeout=10)
+            # Use ternary to select SMTP class based on TLS mode
+            smtp = (smtplib.SMTP_SSL if (self.use_tls and not self.opportunistic_tls) else smtplib.SMTP)(
+                self.server, self.port, timeout=10, local_hostname=local_host or None
+            )
+
+            assert smtp is not None
+            if self.use_tls and self.opportunistic_tls:
+                smtp.ehlo(local_host)
+                smtp.starttls()
+                smtp.ehlo(local_host)
 
             # Only authenticate if both username and password are non-empty
             if self.username and self.password and self.username.strip() and self.password.strip():

api/tests/integration_tests/.env.example

@@ -103,6 +103,8 @@ SMTP_USERNAME=123
 SMTP_PASSWORD=abc
 SMTP_USE_TLS=true
 SMTP_OPPORTUNISTIC_TLS=false
+# Optional: override the local hostname used for SMTP HELO/EHLO
+SMTP_LOCAL_HOSTNAME=
 
 # Sentry configuration
 SENTRY_DSN=

api/tests/unit_tests/libs/test_smtp_client.py

@@ -1,4 +1,4 @@
-from unittest.mock import MagicMock, patch
+from unittest.mock import ANY, MagicMock, patch
 
 import pytest
 
@@ -17,7 +17,7 @@ def test_smtp_plain_success(mock_smtp_cls: MagicMock):
     client = SMTPClient(server="smtp.example.com", port=25, username="", password="", _from="noreply@example.com")
     client.send(_mail())
 
-    mock_smtp_cls.assert_called_once_with("smtp.example.com", 25, timeout=10)
+    mock_smtp_cls.assert_called_once_with("smtp.example.com", 25, timeout=10, local_hostname=ANY)
     mock_smtp.sendmail.assert_called_once()
     mock_smtp.quit.assert_called_once()
 
@@ -38,7 +38,7 @@ def test_smtp_tls_opportunistic_success(mock_smtp_cls: MagicMock):
     )
     client.send(_mail())
 
-    mock_smtp_cls.assert_called_once_with("smtp.example.com", 587, timeout=10)
+    mock_smtp_cls.assert_called_once_with("smtp.example.com", 587, timeout=10, local_hostname=ANY)
     assert mock_smtp.ehlo.call_count == 2
     mock_smtp.starttls.assert_called_once()
     mock_smtp.login.assert_called_once_with("user", "pass")

api/tests/unit_tests/tasks/test_mail_send_task.py

@@ -9,7 +9,7 @@
 """
 
 import smtplib
-from unittest.mock import MagicMock, patch
+from unittest.mock import ANY, MagicMock, patch
 
 import pytest
 
@@ -151,7 +151,7 @@ def test_smtp_send_with_tls_ssl(self, mock_smtp_ssl):
         client.send(mail_data)
 
         # Assert
-        mock_smtp_ssl.assert_called_once_with("smtp.example.com", 465, timeout=10)
+        mock_smtp_ssl.assert_called_once_with("smtp.example.com", 465, timeout=10, local_hostname=ANY)
         mock_server.login.assert_called_once_with("user@example.com", "password123")
         mock_server.sendmail.assert_called_once()
         mock_server.quit.assert_called_once()
@@ -181,7 +181,7 @@ def test_smtp_send_with_opportunistic_tls(self, mock_smtp):
         client.send(mail_data)
 
         # Assert
-        mock_smtp.assert_called_once_with("smtp.example.com", 587, timeout=10)
+        mock_smtp.assert_called_once_with("smtp.example.com", 587, timeout=10, local_hostname=ANY)
         mock_server.ehlo.assert_called()
         mock_server.starttls.assert_called_once()
         assert mock_server.ehlo.call_count == 2  # Before and after STARTTLS
@@ -213,7 +213,7 @@ def test_smtp_send_without_tls(self, mock_smtp):
         client.send(mail_data)
 
         # Assert
-        mock_smtp.assert_called_once_with("smtp.example.com", 25, timeout=10)
+        mock_smtp.assert_called_once_with("smtp.example.com", 25, timeout=10, local_hostname=ANY)
         mock_server.login.assert_called_once()
         mock_server.sendmail.assert_called_once()
         mock_server.quit.assert_called_once()

docker/.env.example

@@ -968,6 +968,8 @@ SMTP_USERNAME=
 SMTP_PASSWORD=
 SMTP_USE_TLS=true
 SMTP_OPPORTUNISTIC_TLS=false
+# Optional: override the local hostname used for SMTP HELO/EHLO
+SMTP_LOCAL_HOSTNAME=
 
 # Sendgid configuration
 SENDGRID_API_KEY=

docker/docker-compose.yaml

@@ -425,6 +425,7 @@ x-shared-env: &shared-api-worker-env
   SMTP_PASSWORD: ${SMTP_PASSWORD:-}
   SMTP_USE_TLS: ${SMTP_USE_TLS:-true}
   SMTP_OPPORTUNISTIC_TLS: ${SMTP_OPPORTUNISTIC_TLS:-false}
+  SMTP_LOCAL_HOSTNAME: ${SMTP_LOCAL_HOSTNAME:-}
   SENDGRID_API_KEY: ${SENDGRID_API_KEY:-}
   INDEXING_MAX_SEGMENTATION_TOKENS_LENGTH: ${INDEXING_MAX_SEGMENTATION_TOKENS_LENGTH:-4000}
   INVITE_EXPIRY_HOURS: ${INVITE_EXPIRY_HOURS:-72}