diff --git a/program/lib/Roundcube/rcube_text2html.php b/program/lib/Roundcube/rcube_text2html.php
index 2ffe5301d..5c240d515 100644
--- a/program/lib/Roundcube/rcube_text2html.php
+++ b/program/lib/Roundcube/rcube_text2html.php
@@ -46,10 +46,6 @@ class rcube_text2html
     protected $config = array(
         // non-breaking space
         'space' => "\xC2\xA0",
-        // word-joiner (zero-width no-break space)
-        // 'wordjoiner' => "\xEF\xBB\xBF", // U+2060
-        // use deprecated U+FEFF character because of webkit issue with displaying U+2060 (#1490353)
-        'wordjoiner' => "\xEF\xBB\xBF", // U+FEFF
         // enables format=flowed parser
         'flowed' => false,
         // enables wrapping for non-flowed text
@@ -63,6 +59,9 @@ class rcube_text2html
         'links' => true,
         // string replacer class
         'replacer' => 'rcube_string_replacer',
+        // prefix and suffix of unwrappable line
+        'nobr_start' => '<span style="white-space:nowrap">',
+        'nobr_end'   => '</span>',
     );
 
 
@@ -281,12 +280,11 @@ class rcube_text2html
         // replace HTML special characters
         $text = strtr($text, $table);
 
-        $nbsp = $this->config['space'];
-        $nobr = $this->config['wordjoiner'];
-
         // replace some whitespace characters
         $text = str_replace(array("\r", "\t"), array('', '    '), $text);
 
+        $nbsp = $this->config['space'];
+
         // replace spaces with non-breaking spaces
         if ($is_flowed) {
             $pos  = 0;
@@ -304,15 +302,13 @@ class rcube_text2html
 
             $text = $copy;
         }
-        // make the whole line non-breakable
-        else {
-            $repl = array(
-                ' ' => $nbsp,
-                '-' => $nobr . '-' . $nobr,
-                '/' => $nobr . '/',
-            );
-
-            $text = str_replace(array_keys($repl), array_values($repl), $text);
+        // make the whole line non-breakable if needed
+        else if ($text !== '' && preg_match('/[^a-zA-Z0-9_]/', $text)) {
+            // use non-breakable spaces to correctly display
+            // trailing/leading spaces and multi-space inside
+            $text = str_replace(' ', $nbsp, $text);
+            // wrap in nobr element, so it's not wrapped on e.g. - or /
+            $text = $this->config['nobr_start'] . $text .  $this->config['nobr_end'];
         }
 
         return $text;
diff --git a/tests/Framework/Text2Html.php b/tests/Framework/Text2Html.php
index 771e14703..a08f9c036 100644
--- a/tests/Framework/Text2Html.php
+++ b/tests/Framework/Text2Html.php
@@ -21,49 +21,53 @@ class Framework_Text2Html extends PHPUnit_Framework_TestCase
             'flowed' => false,
             'wrap'   => false,
             'space'  => '_', // replace UTF-8 non-breaking space for simpler testing
+            'nobr_start' => '>',
+            'nobr_end'   => '<',
         );
 
-        $data[] = array(" aaaa", "_aaaa", $options);
-        $data[] = array("aaaa aaaa", "aaaa_aaaa", $options);
-        $data[] = array("aaaa  aaaa", "aaaa__aaaa", $options);
-        $data[] = array("aaaa   aaaa", "aaaa___aaaa", $options);
-        $data[] = array("aaaa\taaaa", "aaaa____aaaa", $options);
+        $data[] = array(" aaaa", ">_aaaa<", $options);
+        $data[] = array("aa>aa", ">aa&gt;aa<", $options);
+        $data[] = array("aaaa aaaa", ">aaaa_aaaa<", $options);
+        $data[] = array("aaaa  aaaa", ">aaaa__aaaa<", $options);
+        $data[] = array("aaaa   aaaa", ">aaaa___aaaa<", $options);
+        $data[] = array("aaaa\taaaa", ">aaaa____aaaa<", $options);
         $data[] = array("aaaa\naaaa", "aaaa<br>aaaa", $options);
-        $data[] = array("aaaa\n aaaa", "aaaa<br>_aaaa", $options);
-        $data[] = array("aaaa\n  aaaa", "aaaa<br>__aaaa", $options);
-        $data[] = array("aaaa\n   aaaa", "aaaa<br>___aaaa", $options);
-        $data[] = array("\taaaa", "____aaaa", $options);
+        $data[] = array("aaaa\n aaaa", "aaaa<br>>_aaaa<", $options);
+        $data[] = array("aaaa\n  aaaa", "aaaa<br>>__aaaa<", $options);
+        $data[] = array("aaaa\n   aaaa", "aaaa<br>>___aaaa<", $options);
+        $data[] = array("\n", "<br>", $options);
+        $data[] = array("\taaaa", ">____aaaa<", $options);
         $data[] = array("\naaaa", "<br>aaaa", $options);
-        $data[] = array("\n aaaa", "<br>_aaaa", $options);
-        $data[] = array("\n  aaaa", "<br>__aaaa", $options);
-        $data[] = array("\n   aaaa", "<br>___aaaa", $options);
+        $data[] = array("\n aaaa", "<br>>_aaaa<", $options);
+        $data[] = array("\n  aaaa", "<br>>__aaaa<", $options);
+        $data[] = array("\n   aaaa", "<br>>___aaaa<", $options);
         $data[] = array("aaaa\n\nbbbb", "aaaa<br><br>bbbb", $options);
-        $data[] = array(">aaaa \n>aaaa", "<blockquote>aaaa_<br>aaaa</blockquote>", $options);
+        $data[] = array(">aaaa \n>aaaa", "<blockquote>>aaaa_<<br>aaaa</blockquote>", $options);
         $data[] = array(">aaaa\n>aaaa", "<blockquote>aaaa<br>aaaa</blockquote>", $options);
-        $data[] = array(">aaaa \n>bbbb\ncccc dddd", "<blockquote>aaaa_<br>bbbb</blockquote>cccc_dddd", $options);
-        $data[] = array("aaaa-bbbb/cccc", "aaaa\xEF\xBB\xBF-\xEF\xBB\xBFbbbb\xEF\xBB\xBF/cccc", $options);
+        $data[] = array(">aaaa \n>bbbb\ncccc dddd", "<blockquote>>aaaa_<<br>bbbb</blockquote>>cccc_dddd<", $options);
+        $data[] = array("aaaa-bbbb/cccc", ">aaaa-bbbb/cccc<", $options);
 
         $options['flowed'] = true;
 
         $data[] = array(" aaaa", "aaaa", $options);
-        $data[] = array("aaaa aaaa", "aaaa_aaaa", $options);
-        $data[] = array("aaaa  aaaa", "aaaa__aaaa", $options);
-        $data[] = array("aaaa   aaaa", "aaaa___aaaa", $options);
-        $data[] = array("aaaa\taaaa", "aaaa____aaaa", $options);
+        $data[] = array("aaaa aaaa", ">aaaa_aaaa<", $options);
+        $data[] = array("aaaa  aaaa", ">aaaa__aaaa<", $options);
+        $data[] = array("aaaa   aaaa", ">aaaa___aaaa<", $options);
+        $data[] = array("aaaa\taaaa", ">aaaa____aaaa<", $options);
         $data[] = array("aaaa\naaaa", "aaaa<br>aaaa", $options);
         $data[] = array("aaaa\n aaaa", "aaaa<br>aaaa", $options);
-        $data[] = array("aaaa\n  aaaa", "aaaa<br>_aaaa", $options);
-        $data[] = array("aaaa\n   aaaa", "aaaa<br>__aaaa", $options);
-        $data[] = array("\taaaa", "____aaaa", $options);
+        $data[] = array("aaaa\n  aaaa", "aaaa<br>>_aaaa<", $options);
+        $data[] = array("aaaa\n   aaaa", "aaaa<br>>__aaaa<", $options);
+        $data[] = array("\taaaa", ">____aaaa<", $options);
         $data[] = array("\naaaa", "<br>aaaa", $options);
         $data[] = array("\n aaaa", "<br>aaaa", $options);
-        $data[] = array("\n  aaaa", "<br>_aaaa", $options);
-        $data[] = array("\n   aaaa", "<br>__aaaa", $options);
+        $data[] = array("\n  aaaa", "<br>>_aaaa<", $options);
+        $data[] = array("\n   aaaa", "<br>>__aaaa<", $options);
         $data[] = array("aaaa\n\nbbbb", "aaaa<br><br>bbbb", $options);
         $data[] = array(">aaaa \n>aaaa", "<blockquote>aaaa aaaa</blockquote>", $options);
         $data[] = array(">aaaa\n>aaaa", "<blockquote>aaaa<br>aaaa</blockquote>", $options);
-        $data[] = array(">aaaa \n>bbbb\ncccc dddd", "<blockquote>aaaa bbbb</blockquote>cccc_dddd", $options);
-        $data[] = array(chr(0x002).chr(0x003), chr(0x002).chr(0x003), $options);
+        $data[] = array(">aaaa \n>bbbb\ncccc dddd", "<blockquote>aaaa bbbb</blockquote>>cccc_dddd<", $options);
+        $data[] = array("\x02\x03", ">\x02\x03<", $options);
 
         $options['flowed'] = false;
         $options['wrap']   = true;