diff -u b/core/modules/filter/filter.module b/core/modules/filter/filter.module
--- b/core/modules/filter/filter.module
+++ b/core/modules/filter/filter.module
@@ -516,7 +516,7 @@
 
   // Match email addresses.
   // Mail domain pattern differs from the general domain pattern by requiring
-  // a subdomain match. This allows patterns like foo@bar in text without
+  // a TLD match. This allows patterns like foo@bar in text without
   // being converted to a mailto link.
   $email_domain = '(?:[A-Za-z0-9._+-]+\.)+[A-Za-z]{2,64}\b';
   $url_pattern = "[A-Za-z0-9._+-]{1,254}@(?:$email_domain)";
only in patch2:
unchanged:
--- a/core/modules/filter/tests/filter.url-input.txt
+++ b/core/modules/filter/tests/filter.url-input.txt
@@ -9,6 +9,7 @@ This is just a www.test.com. paragraph with person@test.com. some http://www.tes
 http://www.test.com
 www.test.com
 person@test.com
+person@test
 <code>www.test.com</code>
 http://test.com/?search=test
 http://test.com/?search=Test
@@ -28,6 +29,7 @@ The old URL filter has problems with <a title="kind of link www.example.com with
 <dt>www.test.com</dt>
 <dd>http://www.test.com</dd>
 <dd>person@test.com</dd>
+<dd>person@test</dd>
 <dt>check www.test.com</dt>
 <dd>this with some text around: http://www.test.com not so easy person@test.com now?</dd>
 </dl>
only in patch2:
unchanged:
--- a/core/modules/filter/tests/filter.url-output.txt
+++ b/core/modules/filter/tests/filter.url-output.txt
@@ -9,6 +9,7 @@ This is just a <a href="http://www.test.com">www.test.com</a>. paragraph with <a
 <a href="http://www.test.com">http://www.test.com</a>
 <a href="http://www.test.com">www.test.com</a>
 <a href="mailto:person@test.com">person@test.com</a>
+person@test
 <code>www.test.com</code>
 <a href="http://test.com/?search=test">http://test.com/?search=test</a>
 <a href="http://test.com/?search=Test">http://test.com/?search=Test</a>
@@ -28,6 +29,7 @@ The old URL filter has problems with <a title="kind of link www.example.com with
 <dt><a href="http://www.test.com">www.test.com</a></dt>
 <dd><a href="http://www.test.com">http://www.test.com</a></dd>
 <dd><a href="mailto:person@test.com">person@test.com</a></dd>
+<dd>person@test</dd>
 <dt>check <a href="http://www.test.com">www.test.com</a></dt>
 <dd>this with some text around: <a href="http://www.test.com">http://www.test.com</a> not so easy <a href="mailto:person@test.com">person@test.com</a> now?</dd>
 </dl>