diff --git a/src/Endpoint.php b/src/Endpoint.php
index efe961f..60865d9 100644
--- a/src/Endpoint.php
+++ b/src/Endpoint.php
@@ -2,19 +2,39 @@
 
 namespace Lewisdale\Webmentions;
 
+use League\Uri\Exceptions\SyntaxError;
 use Lewisdale\Webmentions\Exceptions\InvalidTargetException;
 use Lewisdale\Webmentions\Exceptions\InvalidUrlException;
 use Lewisdale\Webmentions\Gateways\WebmentionGatewayInterface;
 use Lewisdale\Webmentions\Models\Webmention;
 use Symfony\Component\HttpClient\HttpClient;
+use League\Uri\Uri;
+use Lewisdale\Webmentions\Exceptions\SourceNotFoundException;
+use Lewisdale\Webmentions\Exceptions\TargetNotMentionedException;
+use Symfony\Component\DomCrawler\Crawler;
+use Symfony\Contracts\HttpClient\HttpClientInterface;
 
 class Endpoint {
     private readonly WebmentionGatewayInterface $gateway;
 
-    public function validateUrl(string $url) : bool {
-        return !!filter_var($url, FILTER_VALIDATE_URL);
-    }
+    function __construct(
+        private readonly HttpClientInterface $httpClient
+    )
+    {}
 
+    public function validateUrl(string $url) : bool {
+        try {
+            $uri = Uri::createFromString($url);
+            $scheme = $uri->getScheme();
+            $schemeValid = in_array($scheme, ["http", "https"]);
+
+            return $schemeValid && !!filter_var($url, FILTER_VALIDATE_URL);
+        
+        } catch (SyntaxError $e)
+        {
+            return false;
+        }
+    }
     public function receiveWebmention(string $source, string $target) : void
     {
         // Validate that both source and target are actual domains
@@ -29,21 +49,29 @@ class Endpoint {
         }
 
         // Parse content from the source
-        $client = HttpClient::create();
-        $response = $client->request('GET', $source);
+        $response = $this->httpClient->request('GET', $source);
 
-        if ($response->getStatusCode() === 200)
+        if ($response->getStatusCode() < 400)
         {
-            $content = $this->parseContent($response->getContent());
+            $content = $this->parseContent($response->getContent(), $target);
             $author = $this->parseAuthor($response->getContent());
 
             $webmention = new Webmention(null, $target, $source, $content, $author);
             $this->gateway->save($webmention);
+        } else {
+            throw new SourceNotFoundException();
         }
     }
 
-    private function parseContent(string $content) : ?string
+    private function parseContent(string $content, string $target) : ?string
     {
+        $body = new Crawler($content);
+        $anchors = $body->filter('a[href="'. $target . '"]');
+
+        if (!$anchors->count()) {
+            throw new TargetNotMentionedException();
+        }
+
         return null;
     }
 
diff --git a/src/Exceptions/SourceNotFoundException.php b/src/Exceptions/SourceNotFoundException.php
new file mode 100644
index 0000000..889a24f
--- /dev/null
+++ b/src/Exceptions/SourceNotFoundException.php
@@ -0,0 +1,8 @@
+<?php declare(strict_types=1);
+
+namespace Lewisdale\Webmentions\Exceptions;
+
+use Exception;
+
+class SourceNotFoundException extends Exception {}
+?>
\ No newline at end of file
diff --git a/src/Exceptions/TargetNotMentionedException.php b/src/Exceptions/TargetNotMentionedException.php
new file mode 100644
index 0000000..5a38d3d
--- /dev/null
+++ b/src/Exceptions/TargetNotMentionedException.php
@@ -0,0 +1,8 @@
+<?php declare(strict_types=1);
+
+namespace Lewisdale\Webmentions\Exceptions;
+
+use Exception;
+
+class TargetNotMentionedException extends Exception {}
+?>
\ No newline at end of file
diff --git a/tests/EndpointTest.php b/tests/EndpointTest.php
index 778ef9f..52496de 100644
--- a/tests/EndpointTest.php
+++ b/tests/EndpointTest.php
@@ -1,16 +1,105 @@
 <?php declare(strict_types=1);
 
 use Lewisdale\Webmentions\Endpoint;
+use Lewisdale\Webmentions\Exceptions\InvalidTargetException;
+use Lewisdale\Webmentions\Exceptions\InvalidUrlException;
+use Lewisdale\Webmentions\Exceptions\SourceNotFoundException;
+use Lewisdale\Webmentions\Exceptions\TargetNotMentionedException;
 use PHPUnit\Framework\TestCase;
 use PHPUnit\Framework\Attributes\TestWith;
+use Symfony\Contracts\HttpClient\HttpClientInterface;
+use Symfony\Contracts\HttpClient\ResponseInterface;
 
 class EndpointTest extends TestCase {
     #[TestWith(["https://my.url.com", true])]
     #[TestWith(["my.url.com", false])]
     public function testValidatesUrls(string $url, bool $expected)
     {
-        $endpoint = new Endpoint();
+        $endpoint = new Endpoint($this->createMock(HttpClientInterface::class));
         $this->assertEquals($expected, $endpoint->validateUrl($url), "Expected $url");
     }
+
+    #[TestWith(["https://my-valid-source.url", "htt://my-invalid-target.com"])]
+    #[TestWith(["my-invalid-source", "https://my-valid-target.com"])]
+    #[TestWith(["http:///an-invalid-source", "an-invalid-target"])]
+    public function testThrowsInvalidUrlExceptionIfTheUrlIsInvalid(string $source, string $target)
+    {
+        $this->expectException(InvalidUrlException::class);
+        $endpoint = new Endpoint($this->createMock(HttpClientInterface::class));
+        $endpoint->receiveWebmention($source, $target);
+    }
+
+    public function testThrowsInvalidTargetExceptionIfTheTargetUrlIsNotOnCurrentSite()
+    {
+        $this->expectException(InvalidTargetException::class);
+        $endpoint = new Endpoint($this->createMock(HttpClientInterface::class));
+        $endpoint->receiveWebmention("https://a-valid-source.url", "https://not-my-site.com");
+    }
+
+    #[TestWith([404])]
+    #[TestWith([401])]
+    #[TestWith([500])]
+    #[TestWith([501])]
+    #[TestWith([502])]
+    #[TestWith([503])]
+    #[TestWith([500])]
+    public function testItShouldThrowASourceNotFoundExceptionIfTheSourceUrlIsUnreachable(int $statusCode)
+    {
+        $source = "https://my-valid-source-url.com";
+        $target = "https://lewisdale.dev/post/a-post-page";
+
+        $mockClient = $this->createMock(HttpClientInterface::class);
+        $mockResponse = $this->createMock(ResponseInterface::class);
+
+        $mockClient->expects($this->once())
+            ->method('request')
+            ->with($this->identicalTo('GET'), $this->identicalTo($source))
+            ->will($this->returnValue($mockResponse));
+
+        $mockResponse->method('getStatusCode')
+            ->will($this->returnValue($statusCode));
+
+        $this->expectException(SourceNotFoundException::class);
+
+        $endpoint = new Endpoint($mockClient);
+        $endpoint->receiveWebmention($source, $target);
+    }
+
+    public function testItShouldThrowATargetNotMentionedErrorIfTheSourceDoesNotMentionTheTarget()
+    {
+        $source = "https://my-valid-source-url.com";
+        $target = "https://lewisdale.dev/post/a-post-page";
+
+        $content = <<<XML
+        <html>
+            <head>
+            </head>
+            <body>
+                <h1>Some content</h1>
+                <p>Here's some body content. It <a href="/another/page">contains a url</a>.</p>
+                <p>But it does not mention the target.</p>
+            </body>
+        </html>
+        XML;
+
+        $mockClient = $this->createMock(HttpClientInterface::class);
+        $mockResponse = $this->createMock(ResponseInterface::class);
+
+        $mockClient->expects($this->once())
+            ->method('request')
+            ->with($this->identicalTo('GET'), $this->identicalTo($source))
+            ->will($this->returnValue($mockResponse));
+
+        $mockResponse->method('getStatusCode')
+            ->will($this->returnValue(200));
+
+        $mockResponse->method('getContent')
+            ->willReturn($content);
+
+        $this->expectException(TargetNotMentionedException::class);
+
+        $endpoint = new Endpoint($mockClient);
+        $endpoint->receiveWebmention($source, $target);
+    }
 }
 ?>
\ No newline at end of file