Hi 
That is one reason why it is best to avoid putting spaces in url names.
Anyone who does use a space in a url looks like a clueless moron because
it fails so often. CamelCase works far more often. Spaces don't.
You can see the space has to be replaced by a %20 (coding = space) and that
makes the url look too geeky so most people wont even try to read it. if
there is an 'obvious' error, typo or spelling mistake then they wont be
able to find it. This is exacerbated by the % sign then getting replaced
by the code for % which is %25. Presumably if you pasted that link into
most programs (including LibreOffice Writer as one amongst many) then you
would get from
http://support.mozilla.org/it/kb/Informazioni%20su%20Firefox%20Sync
to
http://support.mozilla.org/it/kb/Informazioni%2520su%2520Firefox%2520Sync
and so on.
Possible work-arounds are to put it in tag-brackets such as
<http://support.mozilla.org/it/kb/Informazioni su Firefox Sync>
or perhaps speechmarks?
"http://support.mozilla.org/it/kb/Informazioni su Firefox Sync"
or in wiki coding-brackets
{http://support.mozilla.org/it/kb/Informazioni su Firefox Sync}
I don't know if any of those work in your email-client or in Writer.
Different programs handle these sorts of things differently so i tend to
give people thebasic link and then tell them how to navigate from there.
eg "
http://support.mozilla.org/it/kb
and look for the link about syncing"
Regards from
Tom