diff --git a/program/lib/Roundcube/rcube_mime.php b/program/lib/Roundcube/rcube_mime.php
index 1e4fac84a..96296a57c 100644
--- a/program/lib/Roundcube/rcube_mime.php
+++ b/program/lib/Roundcube/rcube_mime.php
@@ -622,7 +622,7 @@ class rcube_mime
                 $subString = $substr_func($string, 0, $width, $charset);
 
                 // last line
-                if ($subString === $string) {
+                if ($breakPos === false && $subString === $string) {
                     $cutLength = null;
                 }
                 else {
@@ -652,7 +652,7 @@ class rcube_mime
                         else if ($cut === false) {
                             $spacePos = $strpos_func($string, ' ', 0, $charset);
 
-                            if ($spacePos !== false) {
+                            if ($spacePos !== false && $spacePos < $breakPos) {
                                 $subString = $substr_func($string, 0, $spacePos, $charset);
                                 $cutLength = $spacePos + 1;
                             }
diff --git a/tests/Framework/Mime.php b/tests/Framework/Mime.php
index f15379e5f..61123dd85 100644
--- a/tests/Framework/Mime.php
+++ b/tests/Framework/Mime.php
@@ -181,6 +181,10 @@ class Framework_Mime extends PHPUnit_Framework_TestCase
                 array("abc def", 3, "-"),
                 "abc-def",
             ),
+            array(
+                array("----------------------------------------------------------------------------------------\nabc                        def123456789012345", 76),
+                "----------------------------------------------------------------------------------------\nabc                        def123456789012345",
+            ),
         );
 
         foreach ($samples as $sample) {