To validate all hyperlinks use the link checker. This function validates only
the html part of your email, you have to check all links in the text part
manually.
To start the link checker click in menu Tools on link checker.
Click on "Start link checking" to start the link checker.
please note:
Read the result
All error codes less than 400 are okay, that means URL is correct. Error codes between 400 and 499 means this page doesn't exists or you need a login/password to get access. Any error code greater than 499 indicate problems with this web server.
A list of HTTP error codes you can find on: http://int.supermailer.de/http_reply_codes.htm