Return 550 instead of 421 when rate limited. Rename greylisting to rate limit

app/config.py

@@ -265,7 +265,7 @@ PAGE_LIMIT = 20
 LOCAL_FILE_UPLOAD = "LOCAL_FILE_UPLOAD" in os.environ
 UPLOAD_DIR = None
 
-# Greylisting features
+# Rate Limiting
 # nb max of activity (forward/reply) an alias can have during 1 min
 MAX_ACTIVITY_DURING_MINUTE_PER_ALIAS = 10
 

app/email/rate_limit.py

@@ -11,7 +11,7 @@ from app.log import LOG
 from app.models import Alias, EmailLog, Contact
 
 
-def greylisting_needed_for_alias(alias: Alias) -> bool:
+def rate_limited_for_alias(alias: Alias) -> bool:
     min_time = arrow.now().shift(minutes=-1)
 
     # get the nb of activity on this alias
@@ -37,7 +37,7 @@ def greylisting_needed_for_alias(alias: Alias) -> bool:
     return False
 
 
-def greylisting_needed_for_mailbox(alias: Alias) -> bool:
+def rate_limited_for_mailbox(alias: Alias) -> bool:
     min_time = arrow.now().shift(minutes=-1)
 
     # get nb of activity on this mailbox
@@ -65,13 +65,11 @@ def greylisting_needed_for_mailbox(alias: Alias) -> bool:
     return False
 
 
-def greylisting_needed_forward_phase(alias_address: str) -> bool:
+def rate_limited_forward_phase(alias_address: str) -> bool:
     alias = Alias.get_by(email=alias_address)
 
     if alias:
-        return greylisting_needed_for_alias(alias) or greylisting_needed_for_mailbox(
-            alias
-        )
+        return rate_limited_for_alias(alias) or rate_limited_for_mailbox(alias)
 
     else:
         LOG.d(
@@ -80,29 +78,29 @@ def greylisting_needed_forward_phase(alias_address: str) -> bool:
         )
         alias = try_auto_create(alias_address)
         if alias:
-            return greylisting_needed_for_mailbox(alias)
+            return rate_limited_for_mailbox(alias)
 
     return False
 
 
-def greylisting_needed_reply_phase(reply_email: str) -> bool:
+def rate_limited_reply_phase(reply_email: str) -> bool:
     contact = Contact.get_by(reply_email=reply_email)
     if not contact:
         return False
 
     alias = contact.alias
-    return greylisting_needed_for_alias(alias) or greylisting_needed_for_mailbox(alias)
+    return rate_limited_for_alias(alias) or rate_limited_for_mailbox(alias)
 
 
-def greylisting_needed(mail_from: str, rcpt_tos: [str]) -> bool:
+def rate_limited(mail_from: str, rcpt_tos: [str]) -> bool:
     for rcpt_to in rcpt_tos:
         if is_reply_email(rcpt_to):
-            if greylisting_needed_reply_phase(rcpt_to):
+            if rate_limited_reply_phase(rcpt_to):
                 return True
         else:
             # Forward phase
             address = rcpt_to  # alias@SL
-            if greylisting_needed_forward_phase(address):
+            if rate_limited_forward_phase(address):
                 return True
 
     return False

app/email/status.py

@@ -10,10 +10,10 @@ E206 = "250 SL E206 Out of office"
 
 # 4** errors
 # E401 = "421 SL E401 Retry later"
-E402 = "421 SL E402 Retry later"
-E403 = "421 SL E403 Retry later"
-E404 = "421 SL E404 Retry later"
-E405 = "421 SL E405 Retry later"
+E402 = "421 SL E402 Encryption failed - Retry later"
+# E403 = "421 SL E403 Retry later"
+E404 = "421 SL E404 Unexpected error - Retry later"
+E405 = "421 SL E405 Mailbox domain problem - Retry later"
 E406 = "421 SL E406 Retry later"
 
 # 5** errors
@@ -38,3 +38,7 @@ E518 = "550 SL E518 Disabled mailbox"
 E519 = "550 SL E519 Email detected as spam"
 E520 = "550 SL E520 Email cannot be sent to contact"
 E521 = "550 SL E521 Cannot reach mailbox"
+E522 = (
+    "550 SL E522 The user you are trying to contact is receiving mail "
+    "at a rate that prevents additional messages from being delivered."
+)

email_handler.py

@@ -110,7 +110,7 @@ from app.email_utils import (
     get_queue_id,
 )
 from app.extensions import db
-from app.greylisting import greylisting_needed
+from app.email.rate_limit import rate_limited
 from app.log import LOG, set_message_id
 from app.models import (
     Alias,
@@ -1636,10 +1636,9 @@ def handle(envelope: Envelope) -> str:
         )
         return handle_bounce(envelope, email_log, msg)
 
-    # Whether it's necessary to apply greylisting
-    if greylisting_needed(mail_from, rcpt_tos):
-        LOG.w("Grey listing applied for mail_from:%s rcpt_tos:%s", mail_from, rcpt_tos)
-        return status.E403
+    if rate_limited(mail_from, rcpt_tos):
+        LOG.w("Rate Limiting applied for mail_from:%s rcpt_tos:%s", mail_from, rcpt_tos)
+        return status.E522
 
     # Handle "out of office" auto notice. An automatic response is sent for every forwarded email
     # todo: remove logging

tests/email/test_rate_limit.py

@@ -3,27 +3,27 @@ from app.config import (
     MAX_ACTIVITY_DURING_MINUTE_PER_MAILBOX,
 )
 from app.extensions import db
-from app.greylisting import (
-    greylisting_needed_forward_phase,
-    greylisting_needed_for_alias,
-    greylisting_needed_for_mailbox,
-    greylisting_needed_reply_phase,
+from app.email.rate_limit import (
+    rate_limited_forward_phase,
+    rate_limited_for_alias,
+    rate_limited_for_mailbox,
+    rate_limited_reply_phase,
 )
 from app.models import User, Alias, EmailLog, Contact
 
 
-def test_greylisting_needed_forward_phase_for_alias(flask_client):
+def test_rate_limited_forward_phase_for_alias(flask_client):
     user = User.create(
         email="a@b.c", password="password", name="Test User", activated=True
     )
     db.session.commit()
 
-    # no greylisting for a new alias
+    # no rate limiting for a new alias
     alias = Alias.create_new_random(user)
     db.session.commit()
-    assert not greylisting_needed_for_alias(alias)
+    assert not rate_limited_for_alias(alias)
 
-    # greylisting when there's a previous activity on alias
+    # rate limit when there's a previous activity on alias
     contact = Contact.create(
         user_id=user.id,
         alias_id=alias.id,
@@ -35,10 +35,10 @@ def test_greylisting_needed_forward_phase_for_alias(flask_client):
         EmailLog.create(user_id=user.id, contact_id=contact.id)
         db.session.commit()
 
-    assert greylisting_needed_for_alias(alias)
+    assert rate_limited_for_alias(alias)
 
 
-def test_greylisting_needed_forward_phase_for_mailbox(flask_client):
+def test_rate_limited_forward_phase_for_mailbox(flask_client):
     user = User.create(
         email="a@b.c", password="password", name="Test User", activated=True
     )
@@ -61,20 +61,20 @@ def test_greylisting_needed_forward_phase_for_mailbox(flask_client):
     EmailLog.create(user_id=user.id, contact_id=contact.id)
 
     # Create another alias with the same mailbox
-    # will be greylisted as there's a previous activity on mailbox
+    # will be rate limited as there's a previous activity on mailbox
     alias2 = Alias.create_new_random(user)
     db.session.commit()
-    assert greylisting_needed_for_mailbox(alias2)
+    assert rate_limited_for_mailbox(alias2)
 
 
-def test_greylisting_needed_forward_phase(flask_client):
-    # no greylisting when alias not exist
-    assert not greylisting_needed_forward_phase("not-exist@alias.com")
+def test_rate_limited_forward_phase(flask_client):
+    # no rate limiting when alias does not exist
+    assert not rate_limited_forward_phase("not-exist@alias.com")
 
 
-def test_greylisting_needed_reply_phase(flask_client):
-    # no greylisting when reply_email not exist
-    assert not greylisting_needed_reply_phase("not-exist-reply@alias.com")
+def test_rate_limited_reply_phase(flask_client):
+    # no rate limiting when reply_email does not exist
+    assert not rate_limited_reply_phase("not-exist-reply@alias.com")
 
     user = User.create(
         email="a@b.c", password="password", name="Test User", activated=True
@@ -95,4 +95,4 @@ def test_greylisting_needed_reply_phase(flask_client):
         EmailLog.create(user_id=user.id, contact_id=contact.id)
         db.session.commit()
 
-    assert greylisting_needed_reply_phase("rep@sl.local")
+    assert rate_limited_reply_phase("rep@sl.local")