add unsubscribe header to com emails

app/email_utils.py

@@ -52,7 +52,7 @@ def render(template_name, **kwargs) -> str:
 
 
 def send_welcome_email(user):
-    to_email = user.get_communication_email()
+    to_email, unsubscribe_link, via_email = user.get_communication_email()
     if not to_email:
         return
 
@@ -64,6 +64,8 @@ def send_welcome_email(user):
         f"Welcome to SimpleLogin {user.name}",
         render("com/welcome.txt", name=user.name, user=user, alias=alias),
         render("com/welcome.html", name=user.name, user=user, alias=alias),
+        unsubscribe_link,
+        via_email,
     )
 
 
@@ -186,7 +188,14 @@ def send_cannot_create_domain_alias(user, alias, domain):
     )
 
 
-def send_email(to_email, subject, plaintext, html=None):
+def send_email(
+    to_email,
+    subject,
+    plaintext,
+    html=None,
+    unsubscribe_link=None,
+    unsubscribe_via_email=False,
+):
     if NOT_SEND_EMAIL:
         LOG.d(
             "send email with subject '%s' to '%s', plaintext: %s",
@@ -221,6 +230,13 @@ def send_email(to_email, subject, plaintext, html=None):
     date_header = formatdate()
     msg["Date"] = date_header
 
+    if unsubscribe_link:
+        add_or_replace_header(msg, "List-Unsubscribe", f"<{unsubscribe_link}>")
+        if not unsubscribe_via_email:
+            add_or_replace_header(
+                msg, "List-Unsubscribe-Post", "List-Unsubscribe=One-Click"
+            )
+
     # add DKIM
     email_domain = SUPPORT_EMAIL[SUPPORT_EMAIL.find("@") + 1 :]
     add_dkim_signature(msg, email_domain)

app/models.py

@@ -24,6 +24,7 @@ from app.config import (
     LANDING_PAGE_URL,
     FIRST_ALIAS_DOMAIN,
     DISABLE_ONBOARDING,
+    UNSUBSCRIBER,
 )
 from app.errors import AliasInTrashError
 from app.extensions import db
@@ -538,21 +539,29 @@ class User(db.Model, ModelMixin, UserMixin):
     def two_factor_authentication_enabled(self) -> bool:
         return self.enable_otp or self.fido_enabled()
 
-    def get_communication_email(self) -> Optional[str]:
-        """return the email that user uses to receive email communication"""
+    def get_communication_email(self) -> (Optional[str], str, bool):
+        """
+        Return
+        - the email that user uses to receive email communication. None if user unsubscribes from newsletter
+        - the unsubscribe URL
+        - whether the unsubscribe method is via sending email (mailto:) or Http POST
+        """
         if self.notification and self.activated:
             if self.newsletter_alias_id:
                 alias = Alias.get(self.newsletter_alias_id)
                 if alias.enabled:
-                    return alias.email
-
-                # user doesn't want to receive newsletter
+                    unsubscribe_link, via_email = alias.unsubscribe_link()
+                    return alias.email, unsubscribe_link, via_email
+                # alias disabled -> user doesn't want to receive newsletter
                 else:
-                    return None
+                    return None, None, False
             else:
-                return self.email
+                # do not handle http POST unsubscribe
+                if UNSUBSCRIBER:
+                    # use * as suffix instead of = as for alias unsubscribe
+                    return self.email, f"mailto:{UNSUBSCRIBER}?subject={self.id}*", True
 
-        return None
+        return None, None, False
 
     def available_sl_domains(self) -> [str]:
         """

job_runner.py

@@ -52,7 +52,7 @@ def new_app():
 
 
 def onboarding_send_from_alias(user):
-    to_email = user.get_communication_email()
+    to_email, unsubscribe_link, via_email = user.get_communication_email()
     if not to_email:
         return
 
@@ -61,11 +61,13 @@ def onboarding_send_from_alias(user):
         f"SimpleLogin Tip: Send emails from your alias",
         render("com/onboarding/send-from-alias.txt", user=user, to_email=to_email),
         render("com/onboarding/send-from-alias.html", user=user, to_email=to_email),
+        unsubscribe_link,
+        via_email,
     )
 
 
 def onboarding_pgp(user):
-    to_email = user.get_communication_email()
+    to_email, unsubscribe_link, via_email = user.get_communication_email()
     if not to_email:
         return
 
@@ -74,11 +76,13 @@ def onboarding_pgp(user):
         f"SimpleLogin Tip: Secure your emails with PGP",
         render("com/onboarding/pgp.txt", user=user, to_email=to_email),
         render("com/onboarding/pgp.html", user=user, to_email=to_email),
+        unsubscribe_link,
+        via_email,
     )
 
 
 def onboarding_browser_extension(user):
-    to_email = user.get_communication_email()
+    to_email, unsubscribe_link, via_email = user.get_communication_email()
     if not to_email:
         return
 
@@ -87,11 +91,13 @@ def onboarding_browser_extension(user):
         f"SimpleLogin Tip: Chrome/Firefox/Safari extensions and Android/iOS apps",
         render("com/onboarding/browser-extension.txt", user=user, to_email=to_email),
         render("com/onboarding/browser-extension.html", user=user, to_email=to_email),
+        unsubscribe_link,
+        via_email,
     )
 
 
 def onboarding_mailbox(user):
-    to_email = user.get_communication_email()
+    to_email, unsubscribe_link, via_email = user.get_communication_email()
     if not to_email:
         return
 
@@ -100,6 +106,8 @@ def onboarding_mailbox(user):
         f"SimpleLogin Tip: Multiple mailboxes",
         render("com/onboarding/mailbox.txt", user=user, to_email=to_email),
         render("com/onboarding/mailbox.html", user=user, to_email=to_email),
+        unsubscribe_link,
+        via_email,
     )