diff --git a/src/api/core/accounts.rs b/src/api/core/accounts.rs
index 1dfafca8..35d177d3 100644
--- a/src/api/core/accounts.rs
+++ b/src/api/core/accounts.rs
@@ -775,6 +775,11 @@ async fn post_email_token(data: Json<EmailTokenData>, headers: Headers, mut conn
     }
 
     if User::find_by_mail(&data.new_email, &mut conn).await.is_some() {
+        if CONFIG.mail_enabled() {
+            if let Err(e) = mail::send_change_email_existing(&data.new_email, &user.email).await {
+                error!("Error sending change-email-existing email: {e:#?}");
+            }
+        }
         err!("Email already in use");
     }
 
diff --git a/src/config.rs b/src/config.rs
index bfe94a8f..847c3119 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -1384,6 +1384,7 @@ where
     reg!("email/email_footer_text");
 
     reg!("email/admin_reset_password", ".html");
+    reg!("email/change_email_existing", ".html");
     reg!("email/change_email", ".html");
     reg!("email/delete_account", ".html");
     reg!("email/emergency_access_invite_accepted", ".html");
diff --git a/src/mail.rs b/src/mail.rs
index 8100815e..b1f37886 100644
--- a/src/mail.rs
+++ b/src/mail.rs
@@ -570,6 +570,20 @@ pub async fn send_change_email(address: &str, token: &str) -> EmptyResult {
     send_email(address, &subject, body_html, body_text).await
 }
 
+pub async fn send_change_email_existing(address: &str, acting_address: &str) -> EmptyResult {
+    let (subject, body_html, body_text) = get_text(
+        "email/change_email_existing",
+        json!({
+            "url": CONFIG.domain(),
+            "img_src": CONFIG._smtp_img_src(),
+            "existing_address": address,
+            "acting_address": acting_address,
+        }),
+    )?;
+
+    send_email(address, &subject, body_html, body_text).await
+}
+
 pub async fn send_test(address: &str) -> EmptyResult {
     let (subject, body_html, body_text) = get_text(
         "email/smtp_test",
diff --git a/src/static/templates/email/change_email_existing.hbs b/src/static/templates/email/change_email_existing.hbs
new file mode 100644
index 00000000..ccbcb6ad
--- /dev/null
+++ b/src/static/templates/email/change_email_existing.hbs
@@ -0,0 +1,6 @@
+Your Email Change
+<!---------------->
+A user ({{ acting_address }}) recently tried to change their account to use this email address ({{ existing_address }}). An account already exists with this email ({{ existing_address }}).
+
+If you did not try to change an email address, contact your administrator.
+{{> email/email_footer_text }}
diff --git a/src/static/templates/email/change_email_existing.html.hbs b/src/static/templates/email/change_email_existing.html.hbs
new file mode 100644
index 00000000..aa15f612
--- /dev/null
+++ b/src/static/templates/email/change_email_existing.html.hbs
@@ -0,0 +1,16 @@
+Your Email Change
+<!---------------->
+{{> email/email_header }}
+<table width="100%" cellpadding="0" cellspacing="0" style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 16px; color: #333; line-height: 25px; -webkit-font-smoothing: antialiased; -webkit-text-size-adjust: none;">
+   <tr style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 16px; color: #333; line-height: 25px; -webkit-font-smoothing: antialiased; -webkit-text-size-adjust: none;">
+      <td class="content-block" style="font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 16px; color: #333; line-height: 25px; margin: 0; -webkit-font-smoothing: antialiased; padding: 0 0 10px; -webkit-text-size-adjust: none; text-align: center;" valign="top" align="center">
+         A user ({{ acting_address }}) recently tried to change their account to use this email address ({{ existing_address }}). An account already exists with this email ({{ existing_address }}).
+      </td>
+   </tr>
+   <tr style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 16px; color: #333; line-height: 25px; -webkit-font-smoothing: antialiased; -webkit-text-size-adjust: none;">
+      <td class="content-block last" style="font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 16px; color: #333; line-height: 25px; margin: 0; -webkit-font-smoothing: antialiased; padding: 0; -webkit-text-size-adjust: none; text-align: center;" valign="top" align="center">
+         If you did not try to change an email address, contact your administrator.
+      </td>
+   </tr>
+</table>
+{{> email/email_footer }}