use contact email when generating reply-email

app/api/views/alias.py

@@ -407,7 +407,7 @@ def create_contact_route(alias_id):
         alias_id=alias.id,
         website_email=contact_email,
         name=contact_name,
-        reply_email=generate_reply_email(),
+        reply_email=generate_reply_email(contact_email),
     )
 
     LOG.d("create reverse-alias for %s %s", contact_addr, alias)

app/dashboard/views/alias_contact_manager.py

@@ -203,7 +203,7 @@ def alias_contact_manager(alias_id):
                     alias_id=alias.id,
                     website_email=contact_email,
                     name=contact_name,
-                    reply_email=generate_reply_email(),
+                    reply_email=generate_reply_email(contact_email),
                 )
 
                 LOG.d("create reverse-alias for %s", contact_addr)

app/email_utils.py

@@ -1,5 +1,6 @@
 import email
 import os
+import random
 import re
 from email.header import decode_header
 from email.message import Message
@@ -727,19 +728,37 @@ def add_header(msg: Message, text_header, html_header) -> Message:
     return msg
 
 
-def generate_reply_email() -> str:
+def generate_reply_email(contact_email: str) -> str:
     """
     generate a reply_email (aka reverse-alias), make sure it isn't used by any contact
     """
+    # shorten email to avoid exceeding the 64 characters
+    # from https://tools.ietf.org/html/rfc5321#section-4.5.3
+    # "The maximum total length of a user name or other local-part is 64
+    #    octets."
+
+    if contact_email:
+        # control char: 4 chars (ra+, +)
+        # random suffix: max 10 chars
+        # maximum: 64
+        contact_email = contact_email[:45]
+        contact_email = contact_email.replace("@", ".at.")
+
     # not use while to avoid infinite loop
     for _ in range(1000):
-        reply_email = f"ra+{random_string(25)}@{EMAIL_DOMAIN}"
+        if contact_email:
+            random_length = random.randint(5, 10)
+            reply_email = (
+                f"ra+{contact_email}+{random_string(random_length)}@{EMAIL_DOMAIN}"
+            )
+        else:
+            random_length = random.randint(10, 50)
+            reply_email = f"ra+{random_string(random_length)}@{EMAIL_DOMAIN}"
+
         if not Contact.get_by(reply_email=reply_email):
             return reply_email
 
-    # use UUID as fallback
-    reply_email = f"ra+{uuid4()}@{EMAIL_DOMAIN}"
-    return reply_email
+    raise Exception("Cannot generate reply email")
 
 
 def is_reply_email(address: str) -> bool:

email_handler.py

@@ -213,20 +213,17 @@ def get_or_create_contact(
             contact_from_header,
         )
 
-        reply_email = generate_reply_email()
-
         try:
             contact = Contact.create(
                 user_id=alias.user_id,
                 alias_id=alias.id,
                 website_email=contact_email,
                 name=contact_name,
-                reply_email=reply_email,
                 mail_from=mail_from,
                 from_header=contact_from_header,
             )
             if contact_email:
-                contact.reply_email = generate_reply_email()
+                contact.reply_email = generate_reply_email(contact_email)
             else:
                 LOG.d("Create a contact with invalid email for %s", alias)
                 contact.reply_email = NOREPLY
@@ -281,15 +278,13 @@ def replace_header_when_forward(msg: Message, alias: Alias, header: str):
                 header,
             )
 
-            reply_email = generate_reply_email()
-
             try:
                 contact = Contact.create(
                     user_id=alias.user_id,
                     alias_id=alias.id,
                     website_email=contact_email,
                     name=contact_name,
-                    reply_email=reply_email,
+                    reply_email=generate_reply_email(contact_email),
                     is_cc=header.lower() == "cc",
                     from_header=addr,
                 )

tests/test_email_utils.py

@@ -391,7 +391,15 @@ def test_to_bytes():
 
 
 def test_generate_reply_email(flask_client):
-    reply_email = generate_reply_email()
+    reply_email = generate_reply_email("test@example.org")
+    # return something like
+    # ra+test.at.example.org+gjbnnddll@sl.local
+    assert reply_email.startswith("ra+test.at.example.org+")
+    assert reply_email.endswith(EMAIL_DOMAIN)
+
+    reply_email = generate_reply_email("")
+    # return something like
+    # ra+qdrcxzppngmvtajklnhqvvuyyzgkyityrzjwikk@sl.local
     assert reply_email.startswith("ra+")
     assert reply_email.endswith(EMAIL_DOMAIN)