diff --git a/app/Mailman/Support/MailmanService.php b/app/Mailman/Support/MailmanService.php
index d08a8a66..13df0634 100644
--- a/app/Mailman/Support/MailmanService.php
+++ b/app/Mailman/Support/MailmanService.php
@@ -2,13 +2,33 @@
 
 namespace App\Mailman\Support;
 
+use Illuminate\Http\Client\PendingRequest;
+use Illuminate\Support\Facades\Http;
+
 class MailmanService
 {
+    private string $baseUrl;
+    private string $username;
+    private string $password;
+
     public function setCredentials(string $baseUrl, string $username, string $password): self
     {
+        $this->baseUrl = $baseUrl;
+        $this->username = $username;
+        $this->password = $password;
+
+        return $this;
     }
 
     public function check(): bool
     {
+        $response = $this->http()->get('/system/versions');
+
+        return 200 === $response->status();
+    }
+
+    private function http(): PendingRequest
+    {
+        return Http::withBasicAuth($this->username, $this->password)->withOptions(['base_uri' => $this->baseUrl]);
     }
 }
diff --git a/tests/Unit/Mailman/ServiceTest.php b/tests/Unit/Mailman/ServiceTest.php
new file mode 100644
index 00000000..b1291c27
--- /dev/null
+++ b/tests/Unit/Mailman/ServiceTest.php
@@ -0,0 +1,38 @@
+<?php
+
+namespace Tests\Unit\Mailman;
+
+use App\Mailman\Support\MailmanService;
+use Illuminate\Support\Facades\Http;
+use Tests\TestCase;
+
+class ServiceTest extends TestCase
+{
+    public function testItChecksForCredentials(): void
+    {
+        Http::fake([
+            'http://mailman.test/api/system/versions' => Http::response('', 200),
+        ]);
+
+        $result = app(MailmanService::class)->setCredentials('http://mailman.test/api/', 'user', 'secret')->check();
+
+        $this->assertTrue($result);
+
+        Http::assertSentCount(1);
+        Http::assertSent(fn ($request) => 'GET' === $request->method() && 'http://mailman.test/api/system/versions' === $request->url() && $request->header('Authorization') === ['Basic '.base64_encode('user:secret')]);
+    }
+
+    public function testItFailsWhenChckingCredentials(): void
+    {
+        Http::fake([
+            'http://mailman.test/api/system/versions' => Http::response('', 401),
+        ]);
+
+        $result = app(MailmanService::class)->setCredentials('http://mailman.test/api/', 'user', 'secret')->check();
+
+        $this->assertFalse($result);
+
+        Http::assertSentCount(1);
+        Http::assertSent(fn ($request) => 'GET' === $request->method() && 'http://mailman.test/api/system/versions' === $request->url() && $request->header('Authorization') === ['Basic '.base64_encode('user:secret')]);
+    }
+}