[Outlook.com | Yahoo] prefix id/name attributes on <input>, but does not prefix for attribute on <label>

[husseinalhammad]

Outlook.com and Yahoo prefix the values of the id and/or name attributes on <input> tags, which is reasonable. However, they do not prefix the value of the for attribute on <label> tags.

So the following:

<label for="foo">Label</label>
<input type="text" name="foo" id="foo">

becomes:

<!-- Outlook.com -->
<label for="foo">Label</label>
<input type="text" name="x_foo" id="x_foo">

<!-- Yahoo -->
<label for="foo">Label</label>
<input type="text" name="foo" id="yiv8694647735foo">

[hteumeuleu]

I knew about this in Yahoo but not in Outlook.com! I'm wondering if this is related to a recent update.