How are they 'rejected'? If they're getting through to Outlook.com but simply being sent to your 'Spam' folder then all you should need to do is to go to that folder, click on one of the emails and then on 'Not spam' (or however Outlook.com labels it).
However if they're simply being 'bounced' then it
might be more difficult.
If Outlook.com's server is, for some strange reason, configured to bounce all mail from Tiscali (irrespective of who it's intended for) you might not be able to do anything about it.
But if Outlook.com's server is configured to bounce Tiscali mail directed specifically to your account, you should be able to counter that setting by whitelisting the address that the mail is coming from:
http://www.emailquestions.com/threads/how-to-whitelist-a-contact-in-outlook-com-hotmail.6471/
Better still though, ditch Outlook (which, from its earliest days as Hotmail has always been a lousy service) and get yourself a decent email account ;-)
http://www.gmx.co.uk/