REGEX for URLs and emails

[Magnolee]

Hey there,

I hope someone can help me. I'm currently writing my Bachelor Thesis about digital publications.

I'm trying to find REGEX expression which fasten ePub corrections with Sigil.
What I need is to find an expression which finds URLs and eMail-adresses which are not an actual hyperlink (<a href="...">...</a>) an turn them into one.

FIND:
www.... / http:... oder whatever

Replace with:
<a href=”http://\1">\1</a>

I found this:
(http|ftp|www)(\S+)|(\S+) (\.gov|\.us|\.net|\.com|\.edu|\.org|\.biz)

But unfortunately it includes </p>-Elements or and adresses which already are links.

Can anyone help me with my problem?
Yours sincerely
Magnolee