Index: trunk/roundcubemail/program/steps/mail/sendmail.inc
===================================================================
--- trunk/roundcubemail/program/steps/mail/sendmail.inc	(revision 5068)
+++ trunk/roundcubemail/program/steps/mail/sendmail.inc	(revision 5073)
@@ -145,5 +145,5 @@
 
   // simplified email regexp, supporting quoted local part
-  $email_regexp = '(\S+|("\s*(?:[^"\f\n\r\t\v\b\s]+\s*)+"))@\S+';
+  $email_regexp = '(\S+|("[^"]+"))@\S+';
 
   $regexp  = array('/[,;]\s*[\r\n]+/', '/[\r\n]+/', '/[,;]\s*$/m', '/;/', '/(\S{1})(<'.$email_regexp.'>)/U');