diff --git a/Database/Migrations/2024_07_10_162728_drop_unicity_from_customer_emails.php b/Database/Migrations/2024_07_10_162728_relax_unicity_of_customer_emails.php
similarity index 64%
rename from Database/Migrations/2024_07_10_162728_drop_unicity_from_customer_emails.php
rename to Database/Migrations/2024_07_10_162728_relax_unicity_of_customer_emails.php
index 329fa11..1bbfbb1 100644
--- a/Database/Migrations/2024_07_10_162728_drop_unicity_from_customer_emails.php
+++ b/Database/Migrations/2024_07_10_162728_relax_unicity_of_customer_emails.php
@@ -8,7 +8,7 @@ use Illuminate\Support\Facades\Schema;
 use Illuminate\Database\Schema\Blueprint;
 use Illuminate\Database\Migrations\Migration;
 
-class DropUnicityFromCustomerEmails extends Migration {
+class RelaxUnicityOfCustomerEmails extends Migration {
 	/**
 	 * Run the migrations.
 	 *
@@ -16,6 +16,9 @@ class DropUnicityFromCustomerEmails extends Migration {
 	 */
 	public function up() {
 		Schema::table('emails', function (Blueprint $table) {
+			// Ensure a same e-mail can only be set once for a given Customer.
+			$table->unique(['email', 'customer_id']);
+			// Allow a same e-mail to be set to multiple Customers.
 			$table->dropUnique(['email']);
 		});
 	}
@@ -28,7 +31,10 @@ class DropUnicityFromCustomerEmails extends Migration {
 	public function down() {
 		Schema::table('emails', function (Blueprint $table) {
 			// TODO: Remove all duplicated e-mails.
+			// Restore the unicity of e-mails.
 			$table->unique('email');
+			// Drop the redundant unicity constraint.
+			$table->dropUnique(['email', 'customer_id']);
 		});
 	}
 }