diff --git a/app/account_linking.py b/app/account_linking.py
index 096d2d35..f886453d 100644
--- a/app/account_linking.py
+++ b/app/account_linking.py
@@ -2,13 +2,25 @@ from abc import ABC, abstractmethod
 from arrow import Arrow
 from dataclasses import dataclass
 from enum import Enum
+
+from flask import url_for
 from newrelic import agent
 from typing import Optional
 
+from app import config
 from app.db import Session
+from app.email_utils import send_email_at_most_times, render
 from app.errors import AccountAlreadyLinkedToAnotherPartnerException
 from app.log import LOG
-from app.models import PartnerSubscription, Partner, PartnerUser, User
+from app.models import (
+    PartnerSubscription,
+    Partner,
+    PartnerUser,
+    User,
+    AppleSubscription,
+    Subscription,
+)
+from app.proton.utils import is_proton_partner
 from app.utils import random_string
 
 
@@ -38,6 +50,36 @@ class LinkResult:
     strategy: str
 
 
+def send_double_subscription_if_needed(partner_user: PartnerUser):
+    sub = partner_user.user.get_active_subscription()
+    if isinstance(sub, AppleSubscription):
+        channel = "Apple"
+    elif isinstance(sub, Subscription):
+        channel = "Paddle"
+    else:
+        return
+    send_email_at_most_times(
+        partner_user.user,
+        config.ALERT_DUAL_SUBSCRIPTION_WITH_PARTNER,
+        partner_user.user.email,
+        f"You have two subscriptions in SimpleLogin",
+        render(
+            "transactional/double-subscription-partner.txt.jinja2",
+            is_proton=is_proton_partner(partner_user.partner),
+            partner=partner_user.partner,
+            subscription_channel=channel,
+            cancel_link=url_for("dashboard.billing"),
+        ),
+        render(
+            "transactional/double-subscription-partner.html",
+            is_proton=is_proton_partner(partner_user.partner),
+            partner=partner_user.partner,
+            subscription_channel=channel,
+            cancel_link=url_for("dashboard.billing"),
+        ),
+    )
+
+
 def set_plan_for_partner_user(partner_user: PartnerUser, plan: SLPlan):
     sub = PartnerSubscription.get_by(partner_user_id=partner_user.id)
     if plan.type == SLPlanType.Free:
@@ -66,6 +108,7 @@ def set_plan_for_partner_user(partner_user: PartnerUser, plan: SLPlan):
                     "PlanChange", {"plan": "premium", "type": "extension"}
                 )
                 sub.end_at = plan.expiration
+        send_double_subscription_if_needed(partner_user)
     Session.commit()
 
 
diff --git a/app/admin_model.py b/app/admin_model.py
index 3351641e..a3c4122e 100644
--- a/app/admin_model.py
+++ b/app/admin_model.py
@@ -219,7 +219,7 @@ def manual_upgrade(way: str, ids: [int], is_giveaway: bool):
             flash(f"user {user} already has a lifetime license", "warning")
             continue
 
-        sub: Subscription = user.get_subscription()
+        sub: Subscription = user.get_paddle_subscription()
         if sub and not sub.cancelled:
             flash(
                 f"user {user} already has a Paddle license, they have to cancel it first",
diff --git a/app/auth/views/proton.py b/app/auth/views/proton.py
index 53ab5dbd..6d82384f 100644
--- a/app/auth/views/proton.py
+++ b/app/auth/views/proton.py
@@ -19,8 +19,8 @@ from app.proton.proton_client import HttpProtonClient, convert_access_token
 from app.proton.proton_callback_handler import (
     ProtonCallbackHandler,
     Action,
-    get_proton_partner,
 )
+from app.proton.utils import get_proton_partner
 from app.utils import sanitize_next_url
 
 _authorization_base_url = PROTON_BASE_URL + "/oauth/authorize"
diff --git a/app/config.py b/app/config.py
index 558f7c24..d27cf58c 100644
--- a/app/config.py
+++ b/app/config.py
@@ -351,6 +351,8 @@ ALERT_COMPLAINT_TRANSACTIONAL_PHASE = "alert_complaint_transactional_phase"
 
 ALERT_QUARANTINE_DMARC = "alert_quarantine_dmarc"
 
+ALERT_DUAL_SUBSCRIPTION_WITH_PARTNER = "alert_dual_sub_with_partner"
+
 # <<<<< END ALERT EMAIL >>>>
 
 # Disable onboarding emails
diff --git a/app/dashboard/views/billing.py b/app/dashboard/views/billing.py
index a0fa87ee..c3ca4337 100644
--- a/app/dashboard/views/billing.py
+++ b/app/dashboard/views/billing.py
@@ -13,7 +13,7 @@ from app.paddle_utils import cancel_subscription, change_plan
 @login_required
 def billing():
     # sanity check: make sure this page is only for user who has paddle subscription
-    sub: Subscription = current_user.get_subscription()
+    sub: Subscription = current_user.get_paddle_subscription()
 
     if not sub:
         flash("You don't have any active subscription", "warning")
diff --git a/app/dashboard/views/coupon.py b/app/dashboard/views/coupon.py
index 3afe1e19..f022a4d7 100644
--- a/app/dashboard/views/coupon.py
+++ b/app/dashboard/views/coupon.py
@@ -40,7 +40,7 @@ def coupon_route():
     if current_user.lifetime:
         can_use_coupon = False
 
-    sub: Subscription = current_user.get_subscription()
+    sub: Subscription = current_user.get_paddle_subscription()
     if sub:
         can_use_coupon = False
 
diff --git a/app/dashboard/views/delete_account.py b/app/dashboard/views/delete_account.py
index 560bbaa7..42c964ef 100644
--- a/app/dashboard/views/delete_account.py
+++ b/app/dashboard/views/delete_account.py
@@ -14,7 +14,7 @@ from app.models import Subscription, Job
 @sudo_required
 def delete_account():
     if request.method == "POST" and request.form.get("form-name") == "delete-account":
-        sub: Subscription = current_user.get_subscription()
+        sub: Subscription = current_user.get_paddle_subscription()
         # user who has canceled can also re-subscribe
         if sub and not sub.cancelled:
             flash("Please cancel your current subscription first", "warning")
diff --git a/app/dashboard/views/lifetime_licence.py b/app/dashboard/views/lifetime_licence.py
index c348bead..2fc4c56b 100644
--- a/app/dashboard/views/lifetime_licence.py
+++ b/app/dashboard/views/lifetime_licence.py
@@ -23,7 +23,7 @@ def lifetime_licence():
 
     # user needs to cancel active subscription first
     # to avoid being charged
-    sub = current_user.get_subscription()
+    sub = current_user.get_paddle_subscription()
     if sub and not sub.cancelled:
         flash("Please cancel your current subscription first", "warning")
         return redirect(url_for("dashboard.index"))
diff --git a/app/dashboard/views/pricing.py b/app/dashboard/views/pricing.py
index a316ec3e..7bd6334d 100644
--- a/app/dashboard/views/pricing.py
+++ b/app/dashboard/views/pricing.py
@@ -29,7 +29,7 @@ def pricing():
         flash("You already have a lifetime subscription", "error")
         return redirect(url_for("dashboard.index"))
 
-    sub: Subscription = current_user.get_subscription()
+    sub: Subscription = current_user.get_paddle_subscription()
     # user who has canceled can re-subscribe
     if sub and not sub.cancelled:
         flash("You already have an active subscription", "error")
diff --git a/app/dashboard/views/setting.py b/app/dashboard/views/setting.py
index 782be0ca..e20b079c 100644
--- a/app/dashboard/views/setting.py
+++ b/app/dashboard/views/setting.py
@@ -49,8 +49,7 @@ from app.models import (
     AppleSubscription,
     PartnerUser,
 )
-from app.proton.utils import is_connect_with_proton_enabled
-from app.proton.proton_callback_handler import get_proton_partner
+from app.proton.utils import is_connect_with_proton_enabled, get_proton_partner
 from app.utils import random_string, sanitize_email
 
 
diff --git a/app/models.py b/app/models.py
index e5237263..6ccc734f 100644
--- a/app/models.py
+++ b/app/models.py
@@ -8,7 +8,7 @@ import os
 import random
 import uuid
 from email.utils import formataddr
-from typing import List, Tuple, Optional
+from typing import List, Tuple, Optional, Union
 
 import arrow
 import sqlalchemy as sa
@@ -597,57 +597,59 @@ class User(Base, ModelMixin, UserMixin, PasswordOracle):
 
         return user
 
+    def get_active_subscription(
+        self,
+    ) -> Optional[
+        Union[
+            Subscription
+            | AppleSubscription
+            | ManualSubscription
+            | CoinbaseSubscription
+            | PartnerSubscription
+        ]
+    ]:
+        sub: Subscription = self.get_paddle_subscription()
+        if sub:
+            return sub
+
+        apple_sub: AppleSubscription = AppleSubscription.get_by(user_id=self.id)
+        if apple_sub and apple_sub.is_valid():
+            return apple_sub
+
+        manual_sub: ManualSubscription = ManualSubscription.get_by(user_id=self.id)
+        if manual_sub and manual_sub.is_active():
+            return manual_sub
+
+        coinbase_subscription: CoinbaseSubscription = CoinbaseSubscription.get_by(
+            user_id=self.id
+        )
+        if coinbase_subscription and coinbase_subscription.is_active():
+            return coinbase_subscription
+
+        partner_sub: PartnerSubscription = PartnerSubscription.find_by_user_id(self.id)
+        if partner_sub and partner_sub.is_active():
+            return partner_sub
+
+        return None
+
     # region Billing
     def lifetime_or_active_subscription(self) -> bool:
         """True if user has lifetime licence or active subscription"""
         if self.lifetime:
             return True
 
-        sub: Subscription = self.get_subscription()
-        if sub:
-            return True
-
-        apple_sub: AppleSubscription = AppleSubscription.get_by(user_id=self.id)
-        if apple_sub and apple_sub.is_valid():
-            return True
-
-        manual_sub: ManualSubscription = ManualSubscription.get_by(user_id=self.id)
-        if manual_sub and manual_sub.is_active():
-            return True
-
-        coinbase_subscription: CoinbaseSubscription = CoinbaseSubscription.get_by(
-            user_id=self.id
-        )
-        if coinbase_subscription and coinbase_subscription.is_active():
-            return True
-
-        partner_sub: PartnerSubscription = PartnerSubscription.find_by_user_id(self.id)
-        if partner_sub and partner_sub.is_active():
-            return True
-
-        return False
+        return self.get_active_subscription() is not None
 
     def is_paid(self) -> bool:
         """same as _lifetime_or_active_subscription but not include free manual subscription"""
-        sub: Subscription = self.get_subscription()
-        if sub:
-            return True
+        sub = self.get_active_subscription()
+        if sub is None:
+            return False
 
-        apple_sub: AppleSubscription = AppleSubscription.get_by(user_id=self.id)
-        if apple_sub and apple_sub.is_valid():
-            return True
+        if isinstance(sub, ManualSubscription) and sub.is_giveaway():
+            return False
 
-        manual_sub: ManualSubscription = ManualSubscription.get_by(user_id=self.id)
-        if manual_sub and not manual_sub.is_giveaway and manual_sub.is_active():
-            return True
-
-        coinbase_subscription: CoinbaseSubscription = CoinbaseSubscription.get_by(
-            user_id=self.id
-        )
-        if coinbase_subscription and coinbase_subscription.is_active():
-            return True
-
-        return False
+        return True
 
     def in_trial(self):
         """return True if user does not have lifetime licence or an active subscription AND is in trial period"""
@@ -665,7 +667,7 @@ class User(Base, ModelMixin, UserMixin, PasswordOracle):
 
         if self.lifetime_or_active_subscription():
             # user who has canceled can also re-subscribe
-            sub: Subscription = self.get_subscription()
+            sub: Subscription = self.get_paddle_subscription()
             if sub and sub.cancelled:
                 return True
 
@@ -696,7 +698,7 @@ class User(Base, ModelMixin, UserMixin, PasswordOracle):
         if self.lifetime:
             channels.append("Lifetime")
 
-        sub: Subscription = self.get_subscription()
+        sub: Subscription = self.get_paddle_subscription()
         if sub:
             if sub.cancelled:
                 channels.append(
@@ -779,7 +781,7 @@ class User(Base, ModelMixin, UserMixin, PasswordOracle):
         names = self.name.split(" ")
         return "".join([n[0].upper() for n in names if n])
 
-    def get_subscription(self) -> Optional["Subscription"]:
+    def get_paddle_subscription(self) -> Optional["Subscription"]:
         """return *active* Paddle subscription
         Return None if the subscription is already expired
         TODO: support user unsubscribe and re-subscribe
@@ -3165,6 +3167,7 @@ class PartnerUser(Base, ModelMixin):
     partner_email = sa.Column(sa.String(255), unique=False, nullable=True)
 
     user = orm.relationship(User, foreign_keys=[user_id])
+    partner = orm.relationship(Partner, foreign_keys=[partner_id])
 
     __table_args__ = (
         sa.UniqueConstraint(
diff --git a/app/proton/proton_callback_handler.py b/app/proton/proton_callback_handler.py
index 930a44de..dd504f6d 100644
--- a/app/proton/proton_callback_handler.py
+++ b/app/proton/proton_callback_handler.py
@@ -3,8 +3,7 @@ from enum import Enum
 from flask import url_for
 from typing import Optional
 
-from app.db import Session
-from app.errors import LinkException, ProtonPartnerNotSetUp
+from app.errors import LinkException
 from app.models import User, Partner
 from app.proton.proton_client import ProtonClient, ProtonUser
 from app.account_linking import (
@@ -13,20 +12,6 @@ from app.account_linking import (
     PartnerLinkRequest,
 )
 
-PROTON_PARTNER_NAME = "Proton"
-_PROTON_PARTNER: Optional[Partner] = None
-
-
-def get_proton_partner() -> Partner:
-    global _PROTON_PARTNER
-    if _PROTON_PARTNER is None:
-        partner = Partner.get_by(name=PROTON_PARTNER_NAME)
-        if partner is None:
-            raise ProtonPartnerNotSetUp
-        Session.expunge(partner)
-        _PROTON_PARTNER = partner
-    return _PROTON_PARTNER
-
 
 class Action(Enum):
     Login = 1
diff --git a/app/proton/utils.py b/app/proton/utils.py
index d8421076..fea2c334 100644
--- a/app/proton/utils.py
+++ b/app/proton/utils.py
@@ -1,6 +1,30 @@
+from typing import Optional
+
 from app.config import CONNECT_WITH_PROTON, CONNECT_WITH_PROTON_COOKIE_NAME
 from flask import request
 
+from app.db import Session
+from app.errors import ProtonPartnerNotSetUp
+from app.models import Partner
+
+PROTON_PARTNER_NAME = "Proton"
+_PROTON_PARTNER: Optional[Partner] = None
+
+
+def get_proton_partner() -> Partner:
+    global _PROTON_PARTNER
+    if _PROTON_PARTNER is None:
+        partner = Partner.get_by(name=PROTON_PARTNER_NAME)
+        if partner is None:
+            raise ProtonPartnerNotSetUp
+        Session.expunge(partner)
+        _PROTON_PARTNER = partner
+    return _PROTON_PARTNER
+
+
+def is_proton_partner(partner: Partner) -> str:
+    return partner.name == PROTON_PARTNER_NAME
+
 
 def is_connect_with_proton_enabled() -> bool:
     if CONNECT_WITH_PROTON:
diff --git a/cron.py b/cron.py
index 0c64eac4..bb2ee4e5 100644
--- a/cron.py
+++ b/cron.py
@@ -170,7 +170,7 @@ def notify_manual_sub_end():
             LOG.d("%s has a lifetime licence", user)
             continue
 
-        paddle_sub: Subscription = user.get_subscription()
+        paddle_sub: Subscription = user.get_paddle_subscription()
         if paddle_sub and not paddle_sub.cancelled:
             LOG.d("%s has an active Paddle subscription", user)
             continue
@@ -179,7 +179,7 @@ def notify_manual_sub_end():
             # user can have a (free) manual subscription but has taken a paid subscription via
             # Paddle, Coinbase or Apple since then
             if manual_sub.is_giveaway:
-                if user.get_subscription():
+                if user.get_paddle_subscription():
                     LOG.d("%s has a active Paddle subscription", user)
                     continue
 
diff --git a/init_app.py b/init_app.py
index 331b8f38..39ab099c 100644
--- a/init_app.py
+++ b/init_app.py
@@ -6,7 +6,7 @@ from app.db import Session
 from app.log import LOG
 from app.models import Mailbox, Contact, SLDomain, Partner
 from app.pgp_utils import load_public_key
-from app.proton.proton_callback_handler import PROTON_PARTNER_NAME
+from app.proton.utils import PROTON_PARTNER_NAME
 from server import create_light_app
 
 
diff --git a/templates/emails/transactional/double-subscription-partner.html b/templates/emails/transactional/double-subscription-partner.html
new file mode 100644
index 00000000..e8a379d6
--- /dev/null
+++ b/templates/emails/transactional/double-subscription-partner.html
@@ -0,0 +1,28 @@
+{% extends "base.html" %}
+
+{% block content %}
+  {% call text() %}
+    Hi,
+  {% endcall %}
+
+  {% call text() %}
+    {% if is_proton %}
+    As a Proton user with a paid mail subscription you can have SimpleLogin premium for free, thanks to the SimpleLogin Proton integration.<br>
+    {% else %}
+    {{ partner.name }} has upgraded your account to premium.<br>
+    {% endif %}
+    You currently have a paid SimpleLogin subscription via {{ subscription_channel }}.<br>
+    {% if subscription_channel == 'apple' %}
+    You can cancel it to avoid automatic renewal on your Apple iCloud account page.
+    You can find more info <a href="https://support.apple.com/en-us/HT202039">here</a>.<br>
+    {% elif subscription_channel == 'paddle' %}
+    You can cancel it to avoid automatic renewal on <a href="{{ cancel_link }}">{{ cancel_link }}</a>.<br>
+    {% endif %}
+    You can also keep both subscriptions. In this case there’s nothing to do.
+  {% endcall %}
+
+  {% call text() %}
+    Best, <br>
+    SimpleLogin team.
+  {% endcall %}
+{% endblock %}
diff --git a/templates/emails/transactional/double-subscription-partner.txt.jinja2 b/templates/emails/transactional/double-subscription-partner.txt.jinja2
new file mode 100644
index 00000000..9ad89171
--- /dev/null
+++ b/templates/emails/transactional/double-subscription-partner.txt.jinja2
@@ -0,0 +1,22 @@
+{% extends "base.txt.jinja2" %}
+
+{% block content %}
+Hi,
+
+{% if is_proton -%}
+As a Proton user with a paid mail subscription you can have SimpleLogin premium for free, thanks to the SimpleLogin Proton integration.
+{% else -%}}
+{{ partner.name }} has upgraded your account to premium.
+{% endif -%}
+You currently have a paid SimpleLogin subscription via {subscription_channel}.
+{% if subscription_channel == 'Apple' %}
+You can cancel it to avoid automatic renewal on your Apple iCloud account page.
+Please find more info at https://support.apple.com/en-us/HT202039
+{% elif subscription_channel == 'Paddle' %}
+You can cancel it to avoid automatic renewal on {{ cancel_link }}.
+{% endif %}
+You can also keep both subscriptions. In this case there’s nothing to do.
+
+Best,
+SimpleLogin team.
+{% endblock %}
diff --git a/tests/email_tests/test_rate_limit.py b/tests/email_tests/test_rate_limit.py
index e08573c7..b5f464a2 100644
--- a/tests/email_tests/test_rate_limit.py
+++ b/tests/email_tests/test_rate_limit.py
@@ -1,3 +1,5 @@
+import random
+
 from app.config import (
     MAX_ACTIVITY_DURING_MINUTE_PER_ALIAS,
     MAX_ACTIVITY_DURING_MINUTE_PER_MAILBOX,
@@ -88,11 +90,12 @@ def test_rate_limited_reply_phase(flask_client):
     alias = Alias.create_new_random(user)
     Session.commit()
 
+    reply_email = f"reply-{random.random()}@sl.local"
     contact = Contact.create(
         user_id=user.id,
         alias_id=alias.id,
         website_email="contact@example.com",
-        reply_email="rep@sl.local",
+        reply_email=reply_email,
     )
     Session.commit()
     for _ in range(MAX_ACTIVITY_DURING_MINUTE_PER_ALIAS + 1):
@@ -103,4 +106,4 @@ def test_rate_limited_reply_phase(flask_client):
         )
         Session.commit()
 
-    assert rate_limited_reply_phase("rep@sl.local")
+    assert rate_limited_reply_phase(reply_email)
diff --git a/tests/proton/test_proton_callback_handler.py b/tests/proton/test_proton_callback_handler.py
index 752a874c..fd7f8bbd 100644
--- a/tests/proton/test_proton_callback_handler.py
+++ b/tests/proton/test_proton_callback_handler.py
@@ -6,10 +6,10 @@ from app.account_linking import (
 from app.proton.proton_client import ProtonClient, UserInformation
 from app.proton.proton_callback_handler import (
     ProtonCallbackHandler,
-    get_proton_partner,
     generate_account_not_allowed_to_log_in,
 )
 from app.models import User, PartnerUser
+from app.proton.utils import get_proton_partner
 from app.utils import random_string
 from typing import Optional
 from tests.utils import random_email
diff --git a/tests/test_account_linking.py b/tests/test_account_linking.py
index 5cebb108..c71804dc 100644
--- a/tests/test_account_linking.py
+++ b/tests/test_account_linking.py
@@ -1,6 +1,10 @@
+import random
+
+import arrow
 import pytest
 from arrow import Arrow
 
+from app import config
 from app.account_linking import (
     process_link_case,
     process_login_case,
@@ -13,11 +17,13 @@ from app.account_linking import (
     SLPlanType,
     PartnerLinkRequest,
     ClientMergeStrategy,
+    set_plan_for_partner_user,
 )
-from app.proton.proton_callback_handler import get_proton_partner
+from app.mail_sender import mail_sender
 from app.db import Session
 from app.errors import AccountAlreadyLinkedToAnotherPartnerException
-from app.models import Partner, PartnerUser, User
+from app.models import Partner, PartnerUser, User, Subscription, PlanEnum, SentAlert
+from app.proton.utils import get_proton_partner
 from app.utils import random_string
 
 from tests.utils import random_email
@@ -320,3 +326,39 @@ def test_ensure_partner_user_exists_for_user_raises_exception_when_linked_to_ano
             user,
             partner_2,
         )
+
+
+@mail_sender.store_emails_test_decorator
+def test_send_double_sub_email_is_sent(flask_client):
+    user = create_user(random_email())
+    Subscription.create(
+        user_id=user.id,
+        cancel_url="https://checkout.paddle.com/subscription/cancel?user=1234",
+        update_url="https://checkout.paddle.com/subscription/update?user=1234",
+        subscription_id=int(random.randint(10000, 999999999)),
+        event_time=arrow.now(),
+        next_bill_date=arrow.now().shift(days=10).date(),
+        plan=PlanEnum.monthly,
+        commit=True,
+    )
+    partner = Partner.create(
+        name=random_string(),
+        contact_email=random_email(),
+        flush=True,
+    )
+    partner_user = PartnerUser.create(
+        user_id=user.id,
+        partner_id=partner.id,
+        partner_email=user.email,
+        external_user_id=random_string(),
+        commit=True,
+    )
+    set_plan_for_partner_user(
+        partner_user,
+        SLPlan(type=SLPlanType.Premium, expiration=arrow.now().shift(months=10)),
+    )
+    emails_sent = mail_sender.get_stored_emails()
+    assert len(emails_sent) == 1
+    alerts = SentAlert.filter_by(user_id=user.id).all()
+    assert len(alerts) == 1
+    assert alerts[0].alert_type == config.ALERT_DUAL_SUBSCRIPTION_WITH_PARTNER
diff --git a/tests/test_models.py b/tests/test_models.py
index 586eb15c..8fe4ea6a 100644
--- a/tests/test_models.py
+++ b/tests/test_models.py
@@ -278,12 +278,12 @@ def test_user_get_subscription_grace_period(flask_client):
         commit=True,
     )
 
-    assert user.get_subscription() is not None
+    assert user.get_paddle_subscription() is not None
 
     sub.next_bill_date = (
         arrow.now().shift(days=-(PADDLE_SUBSCRIPTION_GRACE_DAYS + 1)).date()
     )
-    assert user.get_subscription() is None
+    assert user.get_paddle_subscription() is None
 
 
 def test_create_contact_for_noreply(flask_client):