diff --git a/app/auth/templates/auth/register.html b/app/auth/templates/auth/register.html
index 54bc8dbc..1638abe0 100644
--- a/app/auth/templates/auth/register.html
+++ b/app/auth/templates/auth/register.html
@@ -13,6 +13,11 @@
       <div class="form-group">
         <label class="form-label">Email address</label>
         {{ form.email(class="form-control", type="email") }}
+        <div class="small-text alert alert-info">
+          For receiving forwarded emails.
+          This email address needs to be a <b>final</b> email address and can't be an email alias, a disposable or a
+          forwarding email address.
+        </div>
         {{ render_field_errors(form.email) }}
       </div>
 
diff --git a/app/dashboard/templates/dashboard/mailbox.html b/app/dashboard/templates/dashboard/mailbox.html
index a40b2619..252368bc 100644
--- a/app/dashboard/templates/dashboard/mailbox.html
+++ b/app/dashboard/templates/dashboard/mailbox.html
@@ -114,7 +114,7 @@
         {{ new_mailbox_form.email(class="form-control", placeholder="email@example.com") }}
         {{ render_field_errors(new_mailbox_form.email) }}
         <div class="small-text alert alert-info">
-          A mailbox needs to be a <b>final</b> email address and can't be an email alias or a disposable email address.
+          A mailbox needs to be a <b>final</b> email address and can't be an email alias, a disposable or a forwarding email address.
         </div>
 
         <button class="btn btn-lg btn-success mt-2">Create</button>