Mailto Link for Multiple Recipients

I need to link an email mailto link so that there are multiple recipients. After doing some digging online, I am now perplexed. Some are saying to separate by comma, whereas others are saying to use a semicolon.

Which one is the proper way to do this?

Here's my link markup:
<a href="mailto:[email protected]?&[email protected],[email protected]" /></a>

View Replies:
ramonleenders replied on at Permalink Reply
Thunderbird is smart enough to recognize both cases. Depends on the application maybe? No professional in this kinda stuff, but would be awesome if there is THE answer for this.
mhawke replied on at Permalink Reply
The spec for "mailto:" is that it only takes one recipient address so chances are it will fail for some people at some time if you add more than one.

Perhaps set up forwarding or a distribution list?