Question: The question is to know if there is a way to build an HTML email with inline style (no CSS file, nor `<style>` tags) with the href links that react with the mouse passing over them : just to be able to change the color font.

So, no JS, no script, no `<style>`, just `<a href="http://www.dot.com style="....">link</a>`

Answer: 
The normal HTML way for inline styling is:

```
<a href="url" style="color:#cfe7fe";">Click me!</a>

```

But I am not sure how reliable that is in email templates.

You could always try: [(Although deprecated)](http://www.w3schools.com/html/html_fonts.asp)

```
<font color="blue"> <a href="url">Click me!</a> </font>

```

Hope it helps.

**Edit:** For inline hover try using:

```
onmouseover="this.style.color='blue';" 
onmouseout="this.style.color='black';"

```

But again I am not sure on email support for this.
You can, however, you will not be able to change the color of the underline. You can wrap the the link text in a div and then wrap the div in a link, like this:

```
<a href="http://www.google.com"><div style="margin: 0px;padding: 20px 50px;font-size: 50px; color: red;">GOOGLE</div></a>

```

The word "GOOGLE" will appear red, but with a blue underline. So that does not exactly solve your problem, I don't think.