How to check the validity of a URL

Hello: I would like to know if there's any routine to check if a URL is valid, my purpose is have all the links on my web in this form: http://www.myweb.com/checker.php?url=http://www.someurl.com and if http://www.someurl.com is invalid, redirect the user to a friendly page and send me a mail. Is this possible? Best Regards. ------------------------------------------------ QaDRAM, RAD development for the WEB http://www.qadram.com VCLCrawler.com, your VCL search engine http://www.vclcrawler.com W2Kwm, Windows 2000 interface for XWindow http://www.vclcrawler.com/w2kwm/index.htm ebnoud.com, El Boletín No Oficial de Usuarios de Delphi http://www.ebnoud.com