Use a mozilla.org URL for Thunderbird help.

We'll make that url redirect to texturizer.net for now

mail/locales/en-US/chrome/messenger-region/region.properties

@@ -3,7 +3,7 @@
 # mailnews.js
 mailnews.start_page.url=chrome://messenger/locale/start.html
 mailnews.release_notes.url=http://www.mozilla.org/products/thunderbird/releases/
-mailnews.hints_and_tips.url=http://texturizer.net/thunderbird/
+mailnews.hints_and_tips.url=http://www.mozilla.org/support/thunderbird/
 messenger.throbber.url=http://www.mozilla.org/products/thunderbird/
 compose.throbber.url=http://www.mozilla.org/products/thunderbird/
 addressbook.throbber.url=http://www.mozilla.org/products/thunderbird/

mail/locales/en-US/chrome/messenger/start.html

@@ -93,7 +93,7 @@ a:active, a:hover {
 	<li>Address Book</li>
 </ul>
 <h2>More Information</h2>
-<p>For frequently asked questions, tips and general help, visit <a href="http://texturizer.net/thunderbird/">Thunderbird Help</a>.
+<p>For frequently asked questions, tips and general help, visit <a href="http://www.mozilla.org/support/thunderbird/">Thunderbird Help</a>.
 </p>
 <p>For product information, visit the <a href="http://www.mozilla.org/products/thunderbird/">Thunderbird Product Page</a>.
 <div id="gecko"><a href="http://www.mozilla.org/">Powered by Gecko.</a></div>