diff --git a/CHANGELOG b/CHANGELOG
index 27855822748..33deb8214b0 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -35,6 +35,7 @@ CHANGELOG Roundcube Webmail
 - Fix so contactlist_fields option can be set via config file
 - Fix so SPECIAL-USE assignments are forced only until user sets special folders (#4782)
 - Fix performance in reverting order of THREAD result
+- Fix converting mail addresses with @www. into mailto links (#5197)
 
 RELEASE 1.2-beta
 ----------------
diff --git a/program/lib/Roundcube/rcube_string_replacer.php b/program/lib/Roundcube/rcube_string_replacer.php
index eb281ee5408..284d585478c 100644
--- a/program/lib/Roundcube/rcube_string_replacer.php
+++ b/program/lib/Roundcube/rcube_string_replacer.php
@@ -34,6 +34,7 @@ class rcube_string_replacer
     protected $options  = array();
     protected $linkrefs = array();
     protected $urls     = array();
+    protected $noword   = '[^\w@.#-]';
 
 
     function __construct($options = array())
@@ -44,10 +45,13 @@ function __construct($options = array())
         $url1       = '.:;,';
         $url2       = 'a-zA-Z0-9%=#$@+?|!&\\/_~\\[\\]\\(\\){}\*\x80-\xFE-';
 
+        // Supported link prefixes
+        $link_prefix = "([\w]+:\/\/|{$this->noword}[Ww][Ww][Ww]\.|^[Ww][Ww][Ww]\.)";
+
         $this->options         = $options;
         $this->linkref_index   = '/\[([^\]#]+)\](:?\s*##str_replacement_(\d+)##)/';
         $this->linkref_pattern = '/\[([^\]#]+)\]/';
-        $this->link_pattern    = "/([\w]+:\/\/|\W[Ww][Ww][Ww]\.|^[Ww][Ww][Ww]\.)($utf_domain([$url1]*[$url2]+)*)/";
+        $this->link_pattern    = "/$link_prefix($utf_domain([$url1]*[$url2]+)*)/";
         $this->mailto_pattern  = "/("
             ."[-\w!\#\$%&\'*+~\/^`|{}=]+(?:\.[-\w!\#\$%&\'*+~\/^`|{}=]+)*"  // local-part
             ."@$utf_domain"                                                 // domain-part
@@ -91,7 +95,7 @@ public function link_callback($matches)
         if (preg_match('!^(http|ftp|file)s?://!i', $scheme)) {
             $url = $matches[1] . $matches[2];
         }
-        else if (preg_match('/^(\W*)(www\.)$/i', $matches[1], $m)) {
+        else if (preg_match("/^({$this->noword}*)(www\.)$/i", $matches[1], $m)) {
             $url        = $m[2] . $matches[2];
             $url_prefix = 'http://';
             $prefix     = $m[1];
diff --git a/tests/Framework/StringReplacer.php b/tests/Framework/StringReplacer.php
index 7d9600a78c2..543601d35b1 100644
--- a/tests/Framework/StringReplacer.php
+++ b/tests/Framework/StringReplacer.php
@@ -39,6 +39,7 @@ function data_replace()
             array('https://github.com/a/b/compare/3a0f82...1f4b2a after', '<a href="https://github.com/a/b/compare/3a0f82...1f4b2a">https://github.com/a/b/compare/3a0f82...1f4b2a</a> after'),
             array('http://<test>', 'http://<test>'),
             array('http://', 'http://'),
+            array('test@www.test', '<a href="mailto:test@www.test">test@www.test</a>'),
             array('1@1.com www.domain.tld', '<a href="mailto:1@1.com">1@1.com</a> <a href="http://www.domain.tld">www.domain.tld</a>'),
             array(' www.domain.tld ', ' <a href="http://www.domain.tld">www.domain.tld</a> '),
             array(' www.domain.tld/#!download|856p1|2 ', ' <a href="http://www.domain.tld/#!download|856p1|2">www.domain.tld/#!download|856p1|2</a> '),