diff --git a/src/Emails/EditableEmail.php b/src/Emails/EditableEmail.php
new file mode 100644
index 0000000..cb223bd
--- /dev/null
+++ b/src/Emails/EditableEmail.php
@@ -0,0 +1,63 @@
+<?php
+
+declare(strict_types=1);
+
+namespace bkrukowski\TransparentEmail\Emails;
+
+/**
+ * @internal
+ */
+class EditableEmail implements EmailInterface
+{
+    use EmailTrait;
+
+    public function __construct(EmailInterface $email)
+    {
+        $this->localPart = $email->getLocalPart();
+        $this->domain = $email->getDomain();
+    }
+
+    public function removeFromLocalPart(string $toRemove) : EditableEmail
+    {
+        $copy = clone $this;
+        $copy->localPart = str_replace($toRemove, '', $this->localPart);
+
+        return $copy;
+    }
+
+    public function removeSuffixAlias(string $delimiter) : EditableEmail
+    {
+        $copy = clone $this;
+        $copy->localPart = explode($delimiter, $this->localPart, 2)[0];
+
+        return $copy;
+    }
+
+    public function setDomain(string $domain) : EditableEmail
+    {
+        $copy = clone $this;
+        $copy->domain = $domain;
+
+        return $copy;
+    }
+
+    public function setLocalPart(string $localPart) : EditableEmail
+    {
+        $copy = clone $this;
+        $copy->localPart = $localPart;
+
+        return $copy;
+    }
+
+    public function lowerCaseLocalPartIf(bool $condition) : EditableEmail
+    {
+        if ($condition) {
+            $copy = clone $this;
+            $copy->localPart = strtolower($this->localPart);
+
+            return $copy;
+        }
+
+        return $this;
+    }
+}
\ No newline at end of file
diff --git a/src/Emails/MutableEmail.php b/src/Emails/MutableEmail.php
deleted file mode 100644
index c6cda8e..0000000
--- a/src/Emails/MutableEmail.php
+++ /dev/null
@@ -1,56 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace bkrukowski\TransparentEmail\Emails;
-
-/**
- * @internal
- */
-class MutableEmail implements EmailInterface
-{
-    use EmailTrait;
-
-    public function __construct(EmailInterface $email)
-    {
-        $this->localPart = $email->getLocalPart();
-        $this->domain = $email->getDomain();
-    }
-
-    public function removeFromLocalPart(string $toRemove) : MutableEmail
-    {
-        $this->localPart = str_replace($toRemove, '', $this->localPart);
-
-        return $this;
-    }
-
-    public function removeSuffixAlias(string $delimiter) : MutableEmail
-    {
-        $this->localPart = explode($delimiter, $this->localPart, 2)[0];
-
-        return $this;
-    }
-
-    public function setDomain(string $domain) : MutableEmail
-    {
-        $this->domain = $domain;
-
-        return $this;
-    }
-
-    public function setLocalPart(string $localPart) : MutableEmail
-    {
-        $this->localPart = $localPart;
-
-        return $this;
-    }
-
-    public function lowerCaseLocalPartIf(bool $condition) : MutableEmail
-    {
-        if ($condition) {
-            $this->localPart = strtolower($this->localPart);
-        }
-
-        return $this;
-    }
-}
\ No newline at end of file
diff --git a/src/Services/GmailCom.php b/src/Services/GmailCom.php
index 49cc461..b2113bd 100644
--- a/src/Services/GmailCom.php
+++ b/src/Services/GmailCom.php
@@ -4,14 +4,14 @@ declare(strict_types=1);
 
 namespace bkrukowski\TransparentEmail\Services;
 
-use bkrukowski\TransparentEmail\Emails\MutableEmail;
+use bkrukowski\TransparentEmail\Emails\EditableEmail;
 use bkrukowski\TransparentEmail\Emails\EmailInterface;
 
 class GmailCom implements ServiceInterface
 {
     public function getPrimaryEmail(EmailInterface $email) : EmailInterface
     {
-        return (new MutableEmail($email))
+        return (new EditableEmail($email))
             ->removeFromLocalPart('.')
             ->removeSuffixAlias('+')
             ->lowerCaseLocalPartIf(true)
diff --git a/src/Services/MultiDomain.php b/src/Services/MultiDomain.php
index fe33d70..0b2a122 100644
--- a/src/Services/MultiDomain.php
+++ b/src/Services/MultiDomain.php
@@ -4,14 +4,14 @@ declare(strict_types=1);
 
 namespace bkrukowski\TransparentEmail\Services;
 
-use bkrukowski\TransparentEmail\Emails\MutableEmail;
+use bkrukowski\TransparentEmail\Emails\EditableEmail;
 use bkrukowski\TransparentEmail\Emails\EmailInterface;
 
 abstract class MultiDomain implements ServiceInterface
 {
     public function getPrimaryEmail(EmailInterface $email) : EmailInterface
     {
-        return (new MutableEmail($email))
+        return (new EditableEmail($email))
             ->setDomain($this->getPrimaryDomain())
             ->lowerCaseLocalPartIf(!$this->isCaseSensitive());
     }
diff --git a/src/Services/OutlookCom.php b/src/Services/OutlookCom.php
index 60bfdcf..32e6ea2 100644
--- a/src/Services/OutlookCom.php
+++ b/src/Services/OutlookCom.php
@@ -4,14 +4,14 @@ declare(strict_types=1);
 
 namespace bkrukowski\TransparentEmail\Services;
 
-use bkrukowski\TransparentEmail\Emails\MutableEmail;
+use bkrukowski\TransparentEmail\Emails\EditableEmail;
 use bkrukowski\TransparentEmail\Emails\EmailInterface;
 
 class OutlookCom implements ServiceInterface
 {
     public function getPrimaryEmail(EmailInterface $email) : EmailInterface
     {
-        return (new MutableEmail($email))
+        return (new EditableEmail($email))
             ->removeSuffixAlias('+')
             ->lowerCaseLocalPartIf(true);
     }
diff --git a/src/Services/Www33MailCom.php b/src/Services/Www33MailCom.php
index 996eab2..60c7261 100644
--- a/src/Services/Www33MailCom.php
+++ b/src/Services/Www33MailCom.php
@@ -4,14 +4,14 @@ declare(strict_types=1);
 
 namespace bkrukowski\TransparentEmail\Services;
 
-use bkrukowski\TransparentEmail\Emails\MutableEmail;
+use bkrukowski\TransparentEmail\Emails\EditableEmail;
 use bkrukowski\TransparentEmail\Emails\EmailInterface;
 
 class Www33MailCom implements ServiceInterface
 {
     public function getPrimaryEmail(EmailInterface $email) : EmailInterface
     {
-        return (new MutableEmail($email))
+        return (new EditableEmail($email))
             ->setLocalPart(preg_replace('/\\.33mail\\.com$/', '', $email->getDomain()));
     }
 
diff --git a/src/Services/YahooCom.php b/src/Services/YahooCom.php
index 6ff47ef..505fe26 100644
--- a/src/Services/YahooCom.php
+++ b/src/Services/YahooCom.php
@@ -4,14 +4,14 @@ declare(strict_types=1);
 
 namespace bkrukowski\TransparentEmail\Services;
 
-use bkrukowski\TransparentEmail\Emails\MutableEmail;
+use bkrukowski\TransparentEmail\Emails\EditableEmail;
 use bkrukowski\TransparentEmail\Emails\EmailInterface;
 
 class YahooCom implements ServiceInterface
 {
     public function getPrimaryEmail(EmailInterface $email) : EmailInterface
     {
-        return (new MutableEmail($email))
+        return (new EditableEmail($email))
             ->removeSuffixAlias('-')
             ->lowerCaseLocalPartIf(true);
     }
diff --git a/tests/Emails/MutableEmailTest.php b/tests/Emails/EditableEmailTest.php
similarity index 63%
rename from tests/Emails/MutableEmailTest.php
rename to tests/Emails/EditableEmailTest.php
index 05f973d..78e2cf0 100644
--- a/tests/Emails/MutableEmailTest.php
+++ b/tests/Emails/EditableEmailTest.php
@@ -2,11 +2,11 @@
 
 namespace bkrukowski\TransparentEmail\Tests\Emails;
 
-use bkrukowski\TransparentEmail\Emails\MutableEmail;
+use bkrukowski\TransparentEmail\Emails\EditableEmail;
 use bkrukowski\TransparentEmail\Emails\Email;
 use bkrukowski\TransparentEmail\Emails\EmailInterface;
 
-class MutableEmailTest extends \PHPUnit_Framework_TestCase
+class EditableEmailTest extends \PHPUnit_Framework_TestCase
 {
     /**
      * @dataProvider providerRemoveFromLocalPart
@@ -16,10 +16,11 @@ class MutableEmailTest extends \PHPUnit_Framework_TestCase
      */
     public function testRemoveFromLocalPart(EmailInterface $email, string $toRemove)
     {
-        $editable = new MutableEmail($email);
-        $this->assertSame($editable, $editable->removeFromLocalPart($toRemove));
-        $this->assertNotContains((string) $editable, $toRemove);
-        $this->assertSame($email->getDomain(), $editable->getDomain());
+        $editable = new EditableEmail($email);
+        $new = $editable->removeFromLocalPart($toRemove);
+        $this->assertNotSame($editable, $new);
+        $this->assertNotContains((string) $new, $toRemove);
+        $this->assertSame($email->getDomain(), $new->getDomain());
     }
 
     public function providerRemoveFromLocalPart()
@@ -39,9 +40,10 @@ class MutableEmailTest extends \PHPUnit_Framework_TestCase
      */
     public function testRemoveSuffixAlias(EmailInterface $email, string $delimiter, string $expected)
     {
-        $editable = new MutableEmail($email);
-        $this->assertSame($editable, $editable->removeSuffixAlias($delimiter));
-        $this->assertEquals($expected, $editable);
+        $editable = new EditableEmail($email);
+        $new = $editable->removeSuffixAlias($delimiter);
+        $this->assertNotSame($editable, $new);
+        $this->assertEquals($expected, $new);
         $this->assertSame($email->getDomain(), $editable->getDomain());
     }
 
@@ -62,10 +64,11 @@ class MutableEmailTest extends \PHPUnit_Framework_TestCase
      */
     public function testSetDomain(EmailInterface $email, string $domain)
     {
-        $editable = new MutableEmail($email);
-        $this->assertSame($editable, $editable->setDomain($domain));
-        $this->assertSame($domain, $editable->getDomain());
-        $this->assertSame($email->getLocalPart(), $editable->getLocalPart());
+        $editable = new EditableEmail($email);
+        $new = $editable->setDomain($domain);
+        $this->assertNotSame($editable, $new);
+        $this->assertSame($domain, $new->getDomain());
+        $this->assertSame($email->getLocalPart(), $new->getLocalPart());
     }
 
     public function providerSetDomain()
@@ -85,10 +88,11 @@ class MutableEmailTest extends \PHPUnit_Framework_TestCase
      */
     public function testLocalPart(EmailInterface $email, string $localPart)
     {
-        $editable = new MutableEmail($email);
-        $this->assertSame($editable, $editable->setLocalPart($localPart));
-        $this->assertSame($localPart, $editable->getLocalPart());
-        $this->assertSame($email->getDomain(), $editable->getDomain());
+        $editable = new EditableEmail($email);
+        $new = $editable->setLocalPart($localPart);
+        $this->assertNotSame($editable, $new);
+        $this->assertSame($localPart, $new->getLocalPart());
+        $this->assertSame($email->getDomain(), $new->getDomain());
     }
 
     public function providerSetLocalPart()
@@ -105,14 +109,15 @@ class MutableEmailTest extends \PHPUnit_Framework_TestCase
      *
      * @param EmailInterface $email
      * @param bool $condition
-     * @param bool $expected
+     * @param bool $isLowerCase
      */
-    public function testLowerCaseLocalPartIf(EmailInterface $email, bool $condition, bool $expected)
+    public function testLowerCaseLocalPartIf(EmailInterface $email, bool $condition, bool $isLowerCase)
     {
-        $editable = new MutableEmail($email);
-        $this->assertSame($editable, $editable->lowerCaseLocalPartIf($condition));
-        $this->assertSame($expected, strtolower($editable->getLocalPart()) === $editable->getLocalPart());
-        $this->assertSame($email->getDomain(), $editable->getDomain());
+        $editable = new EditableEmail($email);
+        $new = $editable->lowerCaseLocalPartIf($condition);
+        $this->assertSame(!$condition, $editable === $new);
+        $this->assertSame($isLowerCase, strtolower($editable->getLocalPart()) === $new->getLocalPart());
+        $this->assertSame($email->getDomain(), $new->getDomain());
     }
 
     public function providerLowerCaseLocalPartIf()