<p>This is a little confusing to explain, so bear with me here...</p>

<p>I want to set up a system where a user can send templated emails via my website, except it's not actually sent using my server - it instead just opens up their own local mail client with an email ready to go. The application would fill out the body of the email with predefined variables, to save the user having to type it themselves. They can then edit the message as desired, should it not exactly suit their purposes.</p>

<p>There's a number of reasons I want it to go via the user's local mail client, so getting the server to send the email is not an option: it has to be 100% client-side.</p>

<p>I already have a mostly-working solution running, and I'll post the details of that as an answer, I'm wondering if there's any better way?</p>

The way I'm doing it now is basically like this:
The HTML:
```
```
<textarea id="myText">
    Lorem ipsum...
</textarea>
<button onclick="sendMail(); return false">Send</button>
```
```
The Javascript:
```
```
function sendMail() {
    var link = "mailto:me@example.com"
             + "?cc=myCCaddress@example.com"
             + "&subject=" + encodeURIComponent("This is my subject")
             + "&body=" + encodeURIComponent(document.getElementById('myText').value)
    ;
    
    window.location.href = link;
}
```
```
This, surprisingly, works rather well. The only problem is that if the body is particularly long (somewhere over 2000 characters), then it just opens a new email but there's no information in it. I suspect that it'd be to do with the maximum length of the URL being exceeded.