Add BOUNCE_PREFIX, BOUNCE_SUFFIX config

app/config.py

@@ -54,6 +54,12 @@ EMAIL_DOMAIN = os.environ["EMAIL_DOMAIN"].lower()
 SUPPORT_EMAIL = os.environ["SUPPORT_EMAIL"]
 SUPPORT_NAME = os.environ.get("SUPPORT_NAME", "Son from SimpleLogin")
 ADMIN_EMAIL = os.environ.get("ADMIN_EMAIL")
+
+# VERP: mail_from set to BOUNCE_PREFIX + email_log.id + BOUNCE_SUFFIX
+BOUNCE_PREFIX = os.environ.get("BOUNCE_PREFIX") or "bounce+"
+BOUNCE_SUFFIX = os.environ.get("BOUNCE_SUFFIX") or f"+{EMAIL_DOMAIN}"
+BOUNCE_EMAIL = BOUNCE_PREFIX + "{}" + BOUNCE_SUFFIX
+
 try:
     MAX_NB_EMAIL_FREE_PLAN = int(os.environ["MAX_NB_EMAIL_FREE_PLAN"])
 except Exception:

app/email_utils.py

@@ -937,3 +937,7 @@ def should_disable(alias: Alias) -> bool:
     if nb_bounced_last_24h > 5:
         return True
     return False
+
+
+def parse_email_log_id_from_bounce(email_address: str) -> int:
+    return int(email_address[email_address.find("+") : email_address.rfind("+")])

example.env

@@ -39,6 +39,12 @@ SUPPORT_NAME=Son from SimpleLogin
 # in case sender is different than SUPPORT_EMAIL
 SENDER=sender@sl.local
 
+# To use VERP
+# prefix must end with + and suffix must start with +
+# BOUNCE_PREFIX = "bounces+"
+# BOUNCE_SUFFIX = "+@sl.local"
+
+
 # all emails sent to sender are stored in this folder
 SENDER_DIR=/tmp
 

tests/test_email_utils.py

@@ -1,7 +1,7 @@
 import email
 from email.message import EmailMessage
 
-from app.config import MAX_ALERT_24H, EMAIL_DOMAIN
+from app.config import MAX_ALERT_24H, EMAIL_DOMAIN, BOUNCE_EMAIL
 from app.email_utils import (
     get_email_domain_part,
     can_create_directory_for_address,
@@ -24,6 +24,7 @@ from app.email_utils import (
     replace,
     should_disable,
     decode_text,
+    parse_email_log_id_from_bounce,
 )
 from app.extensions import db
 from app.models import User, CustomDomain, Alias, Contact, EmailLog
@@ -615,3 +616,8 @@ def test_should_disable(flask_client):
     alias2 = Alias.create_new_random(user)
     db.session.commit()
     assert not should_disable(alias2)
+
+
+def test_parse_email_log_id_from_bounce():
+    assert parse_email_log_id_from_bounce("bounces+1234+@local") == 1234
+    assert parse_email_log_id_from_bounce(BOUNCE_EMAIL.format(1234)) == 1234