Bug 324992 Add pref UI for mail remote content's new prefs - fix bad grammar just introduced in help file

p=me r=stefanh

extensions/help/resources/locale/en-US/mail_help.xhtml

@@ -558,8 +558,8 @@
     <ul>To block all remote content, uncheck <q>but allow if the sender is in
       this address book:</q>.</ul>
     <ul>To change which address book you use for people who send messages that
-      are allowed to display remote content, then select the correct address
-      book from the drop down.</ul>
+      are allowed to display remote content, select the correct address book
+      from the drop down.</ul>
   </li>
   <li>Click OK to have your change take affect.</li>
 </ol>