diff --git a/app/email_utils.py b/app/email_utils.py
index ef7baa87..c5c21785 100644
--- a/app/email_utils.py
+++ b/app/email_utils.py
@@ -37,7 +37,6 @@ from sqlalchemy import func
 from app.config import (
     ROOT_DIR,
     POSTFIX_SERVER,
-    NOT_SEND_EMAIL,
     DKIM_SELECTOR,
     DKIM_PRIVATE_KEY,
     ALIAS_DOMAINS,
@@ -295,15 +294,6 @@ def send_email(
     from_addr=None,
 ):
     to_email = sanitize_email(to_email)
-    if NOT_SEND_EMAIL:
-        LOG.d(
-            "send email with subject '%s' to '%s', plaintext: %s, html: %s",
-            subject,
-            to_email,
-            plaintext,
-            html,
-        )
-        return
 
     LOG.d("send email to %s, subject '%s'", to_email, subject)
 
diff --git a/app/mail_sender.py b/app/mail_sender.py
index 41c88a14..b8e38221 100644
--- a/app/mail_sender.py
+++ b/app/mail_sender.py
@@ -2,17 +2,12 @@ import time
 from concurrent.futures import ThreadPoolExecutor
 from mailbox import Message
 from smtplib import SMTP, SMTPServerDisconnected, SMTPRecipientsRefused
-from typing import Optional, Dict
+from typing import Optional, Dict, List
 
 import newrelic.agent
 from attr import dataclass
 
-from app.config import (
-    NOT_SEND_EMAIL,
-    POSTFIX_SUBMISSION_TLS,
-    POSTFIX_PORT,
-    POSTFIX_SERVER,
-)
+from app import config
 from app.email import headers
 from app.log import LOG
 from app.message_utils import message_to_bytes
@@ -32,13 +27,26 @@ class SendRequest:
 class MailSender:
     def __init__(self):
         self._pool: Optional[ThreadPoolExecutor] = None
+        self._store_emails = False
+        self._emails_sent: List[SendRequest] = []
+
+    def store_emails_instead_of_sending(self):
+        self._store_emails = True
+
+    def purge_stored_emails(self):
+        self._emails_sent = []
+
+    def get_stored_emails(self) -> List[SendRequest]:
+        return self._emails_sent
 
     def enable_background_pool(self, max_workers=10):
         self._pool = ThreadPoolExecutor(max_workers=max_workers)
 
     def send(self, send_request: SendRequest, retries: int = 2):
         """replace smtp.sendmail"""
-        if NOT_SEND_EMAIL:
+        if self._store_emails:
+            self._emails_sent.append(send_request)
+        if config.NOT_SEND_EMAIL:
             LOG.d(
                 "send email with subject '%s', from '%s' to '%s'",
                 send_request.msg[headers.SUBJECT],
@@ -54,13 +62,13 @@ class MailSender:
     def _send_to_smtp(self, send_request: SendRequest, retries: int):
         try:
             start = time.time()
-            if POSTFIX_SUBMISSION_TLS:
+            if config.POSTFIX_SUBMISSION_TLS:
                 smtp_port = 587
             else:
-                smtp_port = POSTFIX_PORT
+                smtp_port = config.POSTFIX_PORT
 
-            with SMTP(POSTFIX_SERVER, smtp_port) as smtp:
-                if POSTFIX_SUBMISSION_TLS:
+            with SMTP(config.POSTFIX_SERVER, smtp_port) as smtp:
+                if config.POSTFIX_SUBMISSION_TLS:
                     smtp.starttls()
 
                 elapsed = time.time() - start
diff --git a/tests/handler/test_provider_complaints.py b/tests/handler/test_provider_complaints.py
index 8452cd71..7df5879e 100644
--- a/tests/handler/test_provider_complaints.py
+++ b/tests/handler/test_provider_complaints.py
@@ -13,6 +13,7 @@ from app.handler.provider_complaint import (
     handle_hotmail_complaint,
     handle_yahoo_complaint,
 )
+from app.mail_sender import mail_sender
 from app.models import (
     Alias,
     ProviderComplaint,
@@ -61,6 +62,8 @@ def prepare_complaint(
 
 @pytest.mark.parametrize("handle_ftor,provider", origins)
 def test_provider_to_user(flask_client, handle_ftor, provider):
+    mail_sender.store_emails_instead_of_sending()
+    mail_sender.purge_stored_emails()
     user = create_new_user()
     alias = Alias.create_new_random(user)
     Session.commit()
@@ -70,6 +73,8 @@ def test_provider_to_user(flask_client, handle_ftor, provider):
     assert len(found) == 0
     alerts = SentAlert.filter_by(user_id=user.id).all()
     assert len(alerts) == 1
+    sent_mails = mail_sender.get_stored_emails()
+    assert len(sent_mails) == 1
     assert alerts[0].alert_type == f"{ALERT_COMPLAINT_TRANSACTIONAL_PHASE}_{provider}"
 
 
@@ -89,6 +94,8 @@ def test_provider_forward_phase(flask_client, handle_ftor, provider):
 
 @pytest.mark.parametrize("handle_ftor,provider", origins)
 def test_provider_reply_phase(flask_client, handle_ftor, provider):
+    mail_sender.store_emails_instead_of_sending()
+    mail_sender.purge_stored_emails()
     user = create_new_user()
     alias = Alias.create_new_random(user)
     Session.commit()
@@ -98,4 +105,6 @@ def test_provider_reply_phase(flask_client, handle_ftor, provider):
     assert len(found) == 0
     alerts = SentAlert.filter_by(user_id=user.id).all()
     assert len(alerts) == 1
+    sent_mails = mail_sender.get_stored_emails()
+    assert len(sent_mails) == 1
     assert alerts[0].alert_type == f"{ALERT_COMPLAINT_FORWARD_PHASE}_{provider}"