diff --git a/README.md b/README.md
index 01ed70b..5d3eb5a 100644
--- a/README.md
+++ b/README.md
@@ -42,6 +42,8 @@ This will prevent any method name conflicts with core, your custom or other trai
 \Astrotomic\PhpunitAssertions\EmailAssertions::assertValidStrict('gummibeer@astrotomic.info');
 \Astrotomic\PhpunitAssertions\EmailAssertions::assertDomain('astrotomic.info', 'gummibeer@astrotomic.info');
 \Astrotomic\PhpunitAssertions\EmailAssertions::assertLocalPart('gummibeer', 'gummibeer@astrotomic.info');
+\Astrotomic\PhpunitAssertions\EmailAssertions::assertPlusMailbox('gummibeer', 'gummibeer+news@astrotomic.info');
+\Astrotomic\PhpunitAssertions\EmailAssertions::assertPlusAlias('news', 'gummibeer+news@astrotomic.info');
 ```
 
 ### Geographic
diff --git a/src/EmailAssertions.php b/src/EmailAssertions.php
index 4a2780c..50b2cb9 100644
--- a/src/EmailAssertions.php
+++ b/src/EmailAssertions.php
@@ -33,4 +33,20 @@ public static function assertLocalPart(string $expected, $actual): void
         [$localPart] = explode('@', $actual, 2);
         PHPUnit::assertSame($expected, $localPart);
     }
+
+    public static function assertPlusMailbox(string $expected, $actual): void
+    {
+        PHPUnit::assertIsString($actual);
+        [$localPart] = explode('@', $actual, 2);
+        [$mailbox] = explode('+', $localPart, 2);
+        PHPUnit::assertSame($expected, $mailbox);
+    }
+
+    public static function assertPlusAlias(string $expected, $actual): void
+    {
+        PHPUnit::assertIsString($actual);
+        [$localPart] = explode('@', $actual, 2);
+        [$mailbox, $alias] = explode('+', $localPart, 2);
+        PHPUnit::assertSame($expected, $alias);
+    }
 }
diff --git a/tests/EmailAssertionsTest.php b/tests/EmailAssertionsTest.php
index 8658b7b..d6f373d 100644
--- a/tests/EmailAssertionsTest.php
+++ b/tests/EmailAssertionsTest.php
@@ -43,4 +43,30 @@ public static function it_can_validate_local_part(): void
 
         EmailAssertions::assertLocalPart($localPart, $localPart.'@email.com');
     }
+
+    /**
+     * @test
+     * @dataProvider hundredTimes
+     */
+    public static function it_can_validate_plus_mailbox(): void
+    {
+        $mailbox = self::randomString();
+        $alias = self::randomBool();
+        $email = $mailbox.'+'.$alias.'@email.com';
+
+        EmailAssertions::assertPlusMailbox($mailbox, $email);
+    }
+
+    /**
+     * @test
+     * @dataProvider hundredTimes
+     */
+    public static function it_can_validate_plus_alias(): void
+    {
+        $mailbox = self::randomString();
+        $alias = self::randomBool();
+        $email = $mailbox.'+'.$alias.'@email.com';
+
+        EmailAssertions::assertPlusAlias($alias, $email);
+    }
 }