The short answer is, you can't, and you don't want to.
Every page on the web has an address, its URL. If the URL is not accurately input in the browser, the browser can't locate it or connect.
If you'd like to learn more: http://en.wikipedia.org/wiki/Uniform_resource_locator
Updated browsers can usually handle input of just the host name.
So Safari can find "aol.com" -- but a broken URL, such as omitting the "h", is just meaningless text.
Knowing this, there are easy ways to handle your problem. A long, complex url, you might want to copy and paste into Stickies--add the "h" and it will turn into a clickable link.
And perhaps educate your friends as to what a web link, the URL, looks like. If they send you a link that's not broken, it's clickable from the email.