diff --git a/config/generic.json.sample b/config/generic.json.sample
index 3d3eb4f8..544ceb9f 100644
--- a/config/generic.json.sample
+++ b/config/generic.json.sample
@@ -49,7 +49,12 @@
     "smtp_host": "localhost",
     "smtp_port": "25",
     "confirm_message": "Message the users need to confirm before they submit a notification.",
-    "defang_urls": true
+    "defang_urls": true,
+    "deduplicate": {
+        "uuid": true,
+        "hostnames": false,
+        "interval_in_sec": 86400
+    }
   },
   "email_smtp_auth": {
       "auth": false,
diff --git a/lookyloo/lookyloo.py b/lookyloo/lookyloo.py
index 24f39e8c..c03468a8 100644
--- a/lookyloo/lookyloo.py
+++ b/lookyloo/lookyloo.py
@@ -5,6 +5,7 @@ from __future__ import annotations
 import base64
 import copy
 import gzip
+import itertools
 import json
 import logging
 import operator
@@ -869,12 +870,47 @@ class Lookyloo():
 
         return f"Malicious capture according to {len(modules)} module(s): {', '.join(modules)}"
 
+    def already_sent_mail(self, capture_uuid: str, /, uuid_only: bool=True) -> bool:
+        '''Check if a mail was already sent for a specific capture.
+        The check is either done on the UUID only, or on the chain of redirects (if any).
+        In that second case, we take the chain of redirects, keep only the hostnames,
+        aggregate them if the same one is there multiple times in a row (redirect http -> https),
+        and concatenate the remaining ones.
+        True if the mail was already sent in the last 24h, False otherwise.
+        '''
+        if uuid_only:
+            return bool(self.redis.exists(f'sent_mail|{capture_uuid}'))
+        cache = self.capture_cache(capture_uuid)
+        if not cache:
+            return False
+        if hasattr(cache, 'redirects') and cache.redirects:
+            hostnames = [h for h, l in itertools.groupby(urlparse(redirect).hostname for redirect in cache.redirects if urlparse(redirect).hostname) if h is not None]
+            return bool(self.redis.exists(f'sent_mail|{"|".join(hostnames)}'))
+        return False
+
+    def set_sent_mail_key(self, capture_uuid: str, /, deduplicate_interval: int) -> None:
+        '''Set the key for the sent mail in redis'''
+        self.redis.set(f'sent_mail|{capture_uuid}', 1, ex=deduplicate_interval)
+        cache = self.capture_cache(capture_uuid)
+        if cache and hasattr(cache, 'redirects') and cache.redirects:
+            hostnames = [h for h, l in itertools.groupby(urlparse(redirect).hostname for redirect in cache.redirects if urlparse(redirect).hostname) if h is not None]
+            self.redis.set(f'sent_mail|{"|".join(hostnames)}', 1, ex=deduplicate_interval)
+
     def send_mail(self, capture_uuid: str, /, as_admin: bool, email: str | None=None, comment: str | None=None) -> bool | dict[str, Any]:
         '''Send an email notification regarding a specific capture'''
         if not get_config('generic', 'enable_mail_notification'):
             return {"error": "Unable to send mail: mail notification disabled"}
 
         email_config = get_config('generic', 'email')
+        if email_deduplicate := email_config.get('deduplicate'):
+            if email_deduplicate.get('uuid') and self.already_sent_mail(capture_uuid, uuid_only=True):
+                return {"error": "Mail already sent (same UUID)"}
+            if email_deduplicate.get('hostnames') and self.already_sent_mail(capture_uuid, uuid_only=False):
+                return {"error": "Mail already sent (same redirect chain)"}
+            deduplicate_interval = email_deduplicate.get('interval_in_sec')
+        else:
+            deduplicate_interval = 0
+
         smtp_auth = get_config('generic', 'email_smtp_auth')
         redirects = ''
         initial_url = ''
@@ -953,6 +989,8 @@ class Lookyloo():
                             s.starttls()
                     s.login(smtp_auth['smtp_user'], smtp_auth['smtp_pass'])
                 s.send_message(msg)
+                if deduplicate_interval:
+                    self.set_sent_mail_key(capture_uuid, deduplicate_interval)
         except Exception as e:
             self.logger.exception(e)
             self.logger.warning(msg.as_string())
diff --git a/website/web/__init__.py b/website/web/__init__.py
index 689ac782..f88894a4 100644
--- a/website/web/__init__.py
+++ b/website/web/__init__.py
@@ -1161,8 +1161,13 @@ def send_mail(tree_uuid: str) -> WerkzeugResponse:
         # skip clearly incorrect emails
         email = ''
     comment: str = request.form['comment'] if request.form.get('comment') else ''
-    lookyloo.send_mail(tree_uuid, as_admin=flask_login.current_user.is_authenticated, email=email, comment=comment)
-    flash("Email notification sent", 'success')
+    send_status = lookyloo.send_mail(tree_uuid, as_admin=flask_login.current_user.is_authenticated, email=email, comment=comment)
+    if not send_status:
+        flash("Unable to send email notification.", 'error')
+    elif isinstance(send_status, dict) and 'error' in send_status:
+        flash(f"Unable to send email: {send_status['error']}", 'error')
+    else:
+        flash("Email notification sent", 'success')
     return redirect(url_for('tree', tree_uuid=tree_uuid))