fix using too many connections

jdav_web/jdav_web/settings.py

@@ -176,6 +176,13 @@ EMAIL_USE_TLS = True if deployed else False
 EMAIL_BACKEND = 'djcelery_email.backends.CeleryEmailBackend'
 
 
+# Celery Email Setup
+
+CELERY_EMAIL_TASK_CONFIG = {
+    'rate_limit' : '1/m'  # * CELERY_EMAIL_CHUNK_SIZE (default: 10)
+}
+
+
 # Admin setup
 
 ADMINS = (('admin', 'christian@merten-moser.de'),)

jdav_web/mailer/mailutils.py

@@ -20,21 +20,27 @@ def send(subject, content, sender, recipients, message_id=None, reply_to=None,
         headers = {'Message-ID': message_id}
     else:
         headers = {}
-    with mail.get_connection() as connection:
+
+    # construct mails
+    mails = []
     for recipient in set(recipients):
         email = EmailMessage(subject, content, sender, [recipient],
-                                 headers=headers,
-				 connection=connection, **kwargs)
+                             headers=headers, **kwargs)
         if attachments is not None:
             for attach in attachments:
                 email.attach_file(attach)
+        mails.append(email)
     try:
-                email.send(fail_silently=True)
+        # connect to smtp server
+        connection = mail.get_connection()
+        # send all mails with one connection
+        connection.send_messages(mails)
     except Exception as e:
         print("Error when sending mail:", e)
         failed = True
     else:
         succeeded = True
+
     return NOT_SENT if failed and not succeeded else SENT if not failed\
         and succeeded else PARTLY_SENT