Currently only the standard input type=email is documented [1].

As per W3C specification [2] the email input type can have a "multiple" attribute, which should allow to enter multiple email addresses.

I suggest to add a separate evaluation as with input type=file which can have a "multiple" attribute as well and has been documented [3].

I personally don't care whether this feature gets implemented in major browsers, but would opt to document it for completeness (i.e. low priority).

[1] http://caniuse.com/#feat=input-email-tel-url
[2] https://html.spec.whatwg.org/multipage/forms.html#e-mail-state-(type=email)
[3] http://caniuse.com/#feat=input-file-multiple