UnSubscribeURL, OptOutURL doesn't work in Joomla 1.5.x

On clicking UnSubscribe or OptOut buttons redirects to home page of site and doesn't take any action on joomla 1.5.x.

Steps to replicate:
1. Create a mailing containing tokens of unsubscribeurl or optouturl.and submit mailing successfully.
2 These urls are included in received mail by user.
3. When we Unsubscribe or Optout, its get redirected to site home page and contact doesn't get unsubscribed or optout.