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
@@ -537,7 +537,7 @@
   $tasks['_filter_url_parse_full_links'] = $pattern;
 
   // Match email addresses.
-  $url_pattern = "[\p{L}\p{M}\p{N}._-]{1,254}@(?:$domain)";
+  $url_pattern = "[\p{L}\p{M}\p{N}._+-]{1,254}@(?:$domain)";
   $pattern = "`($url_pattern)`u";
   $tasks['_filter_url_parse_email_links'] = $pattern;
 
@@ -567,7 +567,7 @@
   $tasks['_filter_url_parse_full_links'] = $pattern;
 
   // Match email addresses.
-  $url_pattern = "[\p{L}\p{M}\p{N}._+-]{1,254}@(?:$domain)";
+  $url_pattern = "[\p{L}\p{M}\p{N}._-]{1,254}@(?:$domain)";
   $pattern = "`($url_pattern)`u";
   $tasks['_filter_url_parse_email_links'] = $pattern;
 
only in patch2:
unchanged:
--- a/core/modules/filter/src/Tests/FilterUnitTest.php
+++ b/core/modules/filter/src/Tests/FilterUnitTest.php
@@ -515,7 +515,7 @@ function testUrlFilter() {
     // Create a email that is too long.
     $long_email = str_repeat('a', 254) . '@example.com';
     $too_long_email = str_repeat('b', 255) . '@example.com';
-
+    $email_with_plus_sign = 'one+two@example.com';
 
     // Filter selection/pattern matching.
     $tests = array(
@@ -528,12 +528,13 @@ function testUrlFilter() {
       ),
       // MAILTO URLs.
       '
-person@example.com or mailto:person2@example.com or ' . $long_email . ' but not ' . $too_long_email . '
+person@example.com or mailto:person2@example.com or ' . $email_with_plus_sign . ' or ' . $long_email . ' but not ' . $too_long_email . '
 ' => array(
         '<a href="mailto:person@example.com">person@example.com</a>' => TRUE,
         '<a href="mailto:person2@example.com">mailto:person2@example.com</a>' => TRUE,
         '<a href="mailto:' . $long_email . '">' . $long_email . '</a>' => TRUE,
         '<a href="mailto:' . $too_long_email . '">' . $too_long_email . '</a>' => FALSE,
+        '<a href="mailto:' . $email_with_plus_sign . '">' . $email_with_plus_sign . '</a>' => TRUE,
       ),
       // URI parts and special characters.
       '