B. Uncheckable Links

Some links can't be checked because the target url doesn't have an easy method of verification or because the link checker doesn't have the facilities needed for verification. Examples of this include `mailto' and `news' URLs.

Although it's possible to verify, to a certain degree, many mail addresses the only absolute way to check that a mail address reaches the person it's meant to reach is to send a mail and ask for them to reply. Obviously, if everybody checking every link in the world started to do this some unlucky recipients would get very upset at being bombarded with so much mail.

A low level of verification could be done in some circumstances. This requires that the persons actual mail server (the place where their mail is kept) can be contacted directly and is willing to be helpful. This will be implemented in a later version of LinkController.

Checking news urls (not possible at the present moment anyway) requires access to a correctly set up news server which has the feed for that newsgroup. Even then, it doesn't talk about the access for the end user.

Other links cannot be checked because libwww-perl doesn't yet support them. In this case the solution is to add support to libwww-perl.