diff --git a/package-lock.json b/package-lock.json
index fcc6fa760..2f916b83c 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -10361,7 +10361,7 @@
     },
     "packages/core": {
       "name": "@gouvfr-lasuite/proconnect.core",
-      "version": "0.1.0",
+      "version": "0.2.0",
       "license": "MIT",
       "dependencies": {
         "@zootools/email-spell-checker": "^1.12.0",
@@ -10377,7 +10377,7 @@
     },
     "packages/email": {
       "name": "@gouvfr-lasuite/proconnect.email",
-      "version": "0.0.2",
+      "version": "0.1.0",
       "license": "MIT",
       "dependencies": {
         "@kitajs/html": "^4.2.4",
diff --git a/src/connectors/mail.ts b/src/connectors/mail.ts
index c281d8f8a..8c24fce58 100644
--- a/src/connectors/mail.ts
+++ b/src/connectors/mail.ts
@@ -2,7 +2,7 @@
 
 import { convert } from "html-to-text";
 import { createTransport, type SendMailOptions } from "nodemailer";
-import { SMTP_URL } from "../config/env";
+import { DEPLOY_ENV, SMTP_URL } from "../config/env";
 
 //
 
@@ -17,12 +17,28 @@ interface SendMailBrevoOptions extends Omit<SendMailOptions, "from"> {
 }
 export function sendMail(options: SendMailBrevoOptions) {
   const tag = options.tag ? [{ key: "X-Mailin-Tag", value: options.tag }] : [];
+  const subject = computeMailSubject(options.subject);
 
   return transporter.sendMail({
     text:
       typeof options.html === "string" ? convert(options.html) : options.text,
     headers: [...tag],
     ...options,
+    subject,
     from: "nepasrepondre@email.moncomptepro.beta.gouv.fr",
   });
 }
+
+function computeMailSubject(
+  initialSubject: SendMailBrevoOptions["subject"],
+): SendMailBrevoOptions["subject"] {
+  if (initialSubject === undefined) {
+    return undefined;
+  }
+
+  if (DEPLOY_ENV === "sandbox") {
+    return `Test - ${initialSubject}`;
+  }
+
+  return initialSubject;
+}