Update E-Mail Delivery System to Queueing

src/api/login.py

@@ -14,7 +14,7 @@
     SessionConfig,
     r,
     SecurityConfig,
-    send_email,
+    queue_email,
     all_ids,
     regenerate_ids,
     SignupConfig,
@@ -75,8 +75,7 @@ async def forgot_password(
             }
         ),
     )
-    background_tasks.add_task(
-        send_email,
+    queue_email(
         "ChangePassword",
         user["email"],
         code=unique_id,

src/api/signup.py

@@ -1,6 +1,6 @@
 from fastapi import APIRouter, Response, BackgroundTasks, HTTPException, Request
 from api.model import UserSignupRequest, LoginResponse, ConfirmEmailCodeRequest
-from tools import send_email
+from tools import queue_email
 import json
 from tools import SignupConfig, SessionConfig
 from tools import all_ids, regenerate_ids, r
@@ -66,8 +66,7 @@ async def signup(
         )
 
         # Generate and send confirmation email
-        background_tasks.add_task(
-            send_email,
+        queue_email(
             "ConfirmEmail",
             signup_form.email,
             code=unique_id,

src/crud/user.py

@@ -2,7 +2,7 @@
 from tools import (
     users_collection,
     SignupConfig,
-    send_email,
+    queue_email,
     InternalConfig,
     insecure_cols,
     AccountFeaturesConfig,
@@ -155,15 +155,13 @@ def update_public_user(
         # Get a unique ID for confirmation email
         unique_id = all_ids.pop()
         # Generate and send confirmation email
-        background_tasks.add_task(
-            send_email,
+        queue_email(
             "ConfirmEmail",
             data["email"],
             **existing_user,
             code=unique_id,
             time=SignupConfig.conf_code_expiry,
         )
-
         r.setex(
             "emailchange:" + str(existing_user["_id"]),
             SignupConfig.conf_code_expiry * 60,
@@ -335,7 +333,7 @@ def create_user(
     # User Created (Create Session Token and send Welcome Email)
     session_token = sessions.create_login_session(user_db.inserted_id, request)
     if SignupConfig.enable_welcome_email:
-        background_tasks.add_task(send_email, "WelcomeEmail", data["email"], **data)
+        queue_email("WelcomeEmail", data["email"], **data)
     return session_token
 
 

src/tools/__init__.py

@@ -15,7 +15,7 @@
     EmailConfig,
     SignupConfig,
 )
-from .mail import send_email, broadcast_emails
+from .mail import broadcast_emails, queue_email
 from .confirmation_codes import all_ids, regenerate_ids
 
 __all__ = [
@@ -30,7 +30,7 @@
     "AccountFeaturesConfig",
     "insecure_cols",
     "SecurityConfig",
-    "send_email",
+    "queue_email",
     "broadcast_emails",
     "all_ids",
     "regenerate_ids",

src/tools/mail.py

@@ -6,13 +6,31 @@
 from threading import Lock
 from tools import users_collection, InternalConfig
 import importlib
+import re
+import threading
+import queue
 
-smtp = smtplib.SMTP_SSL(EmailConfig.smtp_host, EmailConfig.smtp_port)
+smtp = smtplib.SMTP_SSL(EmailConfig.smtp_host, EmailConfig.smtp_port, timeout=1)
+email_queue = queue.Queue()
+
+
+def queue_email(template_name: str, to: str, **kwargs):
+    email_queue.put_nowait(lambda: send_email(template_name, to, **kwargs))
+
+
+def fill_placeholders(template: str, data: dict) -> str:
+    pattern = re.compile(r"\{\{\s*(\w+)\s*\}\}")
+    result = pattern.sub(
+        lambda match: str(data.get(match.group(1), match.group(0))), template
+    )
+    return result
 
 
 def load_template(template_name: str, **kwargs) -> str:
     with open(f"/src/app/config/email/{template_name}.html", "r") as file:
         template = file.read()
+    if template.find("<title>") == -1:
+        raise ValueError("Template does not contain a title tag")
     subject = template[template.find("<title>") + 7 : template.find("</title>")]
     # Try to find template_name + ".py" and execute the function "preprocess"
     try:
@@ -29,7 +47,7 @@ def load_template(template_name: str, **kwargs) -> str:
                 logger.error(
                     f"Failed to execute preprocess function in {template_name}.py: {e}"
                 )
-    formatted_template = template.format(**kwargs)
+    formatted_template = fill_placeholders(template, kwargs)
     return formatted_template, subject
 
 
@@ -48,7 +66,6 @@ def send_email(template_name: str, to: str, **kwargs):
     # Send email
     smtp.login(EmailConfig.login_usr, EmailConfig.login_pwd)
     smtp.send_message(msg)
-    smtp.quit()
 
     logger.info(f"Email sent to {to} with subject: {subject}")
 
@@ -72,3 +89,17 @@ def broadcast_emails(
         raise e
     finally:
         email_task_lock.release_lock()
+
+
+def email_worker():
+    logger.info("\u001b[32m- E-Mail Worker started\u001b[0m")
+    while True:
+        email_task = email_queue.get()
+        try:
+            email_task()
+        except Exception as e:
+            logger.error(f"Failed to send email: {e}")
+        email_queue.task_done()
+
+
+threading.Thread(target=email_worker).start()