Blank email address error with email field populated

[igarcez]

I always get this error when trying to submit de form

<form id="mc-embedded-subscribe-form" name="mc-embedded-subscribe-form" class="validate" target="_blank" novalidate>
              <div id="mc_embed_signup_scroll">
                <div class="mc-field-group">
                  <input placeholder="Nome:" type="text" value="" name="NAME" class="" id="mce-NAME">
                </div>
                <div class="mc-field-group">
                  <input type="email" placeholder="Email:" value="" name="mce-EMAIL" class="required email" id="mce-EMAIL">
                  <label for="mce-EMAIL"></label>
                </div>
                <div id="mce-responses" class="clear">
                  <div class="response" id="mce-error-response" style="display:none"></div>
                  <div class="response" id="mce-success-response" style="display:none"></div>
                </div>
                <div style="position: absolute; left: -5000px;"><input type="text" name="b_47b7a7b701ac96b4931ab819b_afcd0092c6" tabindex="-1" value=""></div>
                <div class="clear"><input type="submit" value="Cadastre-se" name="subscribe" id="mc-embedded-subscribe" class="button"></div>
              </div>
            </form>

ajax request
params:

_ 1431528300111
c jQuery21404979133804983341_1431528300109
id afcd0092c6
u 47b7a7b701ac96b4931ab819b

[jasondavis]

I have the same issue on some sites and not on others. Trying to find the source of the issue now will share if I do.