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This is discussed more http://webmasters.stackexchange.com/questions/15920/should-plus-be-encoded-in-mailto-hyperlinks, and AFAIK the conclusion is: it is ambiguous spec.

This is discussed more https://webmasters.stackexchange.com/questions/15920/should-plus-be-encoded-in-mailto-hyperlinks, and AFAIK the conclusion is: it is ambiguous spec.

But! Try it in IE/FF/Opera/Chrome etc to see it work/not-work. You might need to test both the "mailto:" handler (i.e. going to an email client), and the "copy email address" that most browsers will add as a context menu. Sigh.

Browser    |             With +           |             With %2b
           | Click link    | Copy address | Click link    | Copy address
-----------+---------------+--------------|---------------|----------------
Chrome 18  | Fail (" ")    | Pass ("+")   | Pass ("+")    | Fail ("%2b")
w/ GMail   |               |              |               |
           |               |              |               | 
IE 9       | Pass ("+")    | N/A          | Pass ("+")    | N/A
w/LiveMail |               |              |               |
           |               |              |               |
Safari 5   | Pass ("+")    | Pass ("+")   | Pass ("+")    | Fail ("%2b")
w/ LiveMail|               |              |               |
           |               |              |               |
Firefox 10 | Pass ("+")    | Pass ("+")   | Pass ("+")    | Pass ("+")
w/ LiveMail|

But! Try it in IE/FF/Safari/Chrome etc to see it work/not-work. You might need to test both the "mailto:" handler (i.e. going to an email client), and the "copy email address" that most browsers will add as a context menu. Sigh.

Browser     |             With +           |             With %2b
            | Click link    | Copy address | Click link    | Copy address
------------+---------------+--------------|---------------|----------------
Chrome 18   | Fail (" ")    | Pass ("+")   | Pass ("+")    | Fail ("%2b")
w/ GMail    |               |              |               |
            |               |              |               | 
IE 9        | Pass ("+")    | N/A          | Pass ("+")    | N/A
w/LiveMail  |               |              |               |
            |               |              |               |
Safari 5    | Pass ("+")    | Pass ("+")   | Pass ("+")    | Fail ("%2b")
w/ LiveMail |               |              |               |
            |               |              |               |
Firefox 10  | Pass ("+")    | Pass ("+")   | Pass ("+")    | Pass ("+")
w/ LiveMail |               |              |               |

So: if we want this to work everywhere, we're going to need per-browser markup, which is - just wrong.

From the table, and the spec, I conclude that mailto:[email protected] is the more right representation, and if only the GMail handler wasn't broken, the world would make sense everywhere.

Blame GMail.

I tested this and logged a bug as soon as the official GMail mailto handler was released. AFAIK, it disappeared into the ether.

Example: http://jsfiddle.net/zmEPe/

Browser    |             With +           |             With %2b
           | Click link    | Copy address | Click link    | Copy address
-----------+---------------+--------------|---------------|----------------
Chrome 18  | Fail (" ")    | Pass ("+")   | Pass ("+")    | Fail ("%2b")
w/ GMail   |               |              |               |
           |               |              |               | 
IE 9       | Pass ("+")    | N/A          | Pass ("+")    | N/A
w/LiveMail |               |              |               |
           |               |              |               |
Safari 5   | Pass ("+")    | Pass ("+")   | Pass ("+")    | Fail ("%2b")
w/ LiveMail|               |              |               |
           |               |              |               |
Firefox 10 | Pass ("+")    | Pass ("+")   | Pass ("+")    | Pass ("+")
w/ LiveMail|