Most e-mail user agents (MUA) consider text in angle brackets as a hyperlink, even and especially in plain text e-mails. So for most cases, just wrap the URL in angle brackets (like this: "bla bla bla - klick this link: <http://www.example.com/once/upon/a/time/there/was/a/file/burried/deep/inside/the/filesystem.txt> bla bla bla") and everything else happens automatically. No need to generate HTML. A properly secured MUA does not use a fully-featured HTML renderer with CSS and JS support, anyway.

Alexander

If you look at the OP, that is what they were trying to do, but there was an accidentally doubled " that kept it from working.

On the other hand generating HTML will work with MUAs that don't automatically hyperlink. And that will work regardless of whether it has support for CSS and JS.