use POSTFIX_PORT instead of 25 if it's set

app/email_utils.py

@@ -26,6 +26,7 @@ from app.config import (
     MAX_NB_EMAIL_FREE_PLAN,
     DISPOSABLE_EMAIL_DOMAINS,
     MAX_ALERT_24H,
+    POSTFIX_PORT,
 )
 from app.dns_utils import get_mx_domains
 from app.extensions import db
@@ -197,7 +198,7 @@ def send_email(
         smtp = SMTP(POSTFIX_SERVER, 587)
         smtp.starttls()
     else:
-        smtp = SMTP(POSTFIX_SERVER, 25)
+        smtp = SMTP(POSTFIX_SERVER, POSTFIX_PORT or 25)
 
     if bounced_email:
         msg = MIMEMultipart("mixed")

email_handler.py

@@ -62,6 +62,7 @@ from app.config import (
     ALERT_BOUNCE_EMAIL,
     ALERT_SPAM_EMAIL,
     ALERT_SPF,
+    POSTFIX_PORT,
 )
 from app.email_utils import (
     send_email,
@@ -1018,7 +1019,7 @@ class MailHandler:
             smtp = SMTP(POSTFIX_SERVER, 587)
             smtp.starttls()
         else:
-            smtp = SMTP(POSTFIX_SERVER, 25)
+            smtp = SMTP(POSTFIX_SERVER, POSTFIX_PORT or 25)
 
         app = new_app()
         with app.app_context():