I need to show loader when ajax calls in mailchimp.

My coding like,

<form action="Myactionname" method="post" id="mc-embedded-subscribe-form" name="mc-embedded-subscribe-form" class="result" target="_blank" novalidate onsubmit="thirdpart();">
          <div class="mc-field-group">
            <!--<label for="mce-EMAIL" class="labelemail">Email Address <span class="asterisk">*</span> </label>-->
            <input type="email" value="" name="EMAIL" class="required email textinputbox" id="mce-EMAIL"
             placeholder="Email Address *" onfocus="this.placeholder=''" onblur="this.placeholder='Email Address *'">
            <input type="submit" value="Sign up" name="signup" id="mc-embedded-subscribe" class="btn_brd" >
          </div>
          <!-- real people should not fill this in and expect good things - do not remove this or risk form bot signups-->
          <div style="position: absolute; left: -5000px;" aria-hidden="true">
            <input type="text" name="b_bc66e7d3354ff8ce99f71a04d_3831086bec" tabindex="-1" value="">
          </div>
        </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>
       
      </form>

<script src="https://s3.amazonaws.com/downloads.mailchimp.com/js/mc-validate.js"></script>

My form validate and submit showing error …

I have an xlsx file with 40,000 emails in column A that I want to import into a new Mailchimp list. In Mailchimp I've checked "Copy and past contacts from .xls or .xlsx file. Then I copied the A column to the clipboard in xlxs and pasted it to the "Paste subscriber" box in MailChimp. The data goes in but when I click Next I get the error "You must have an email address column to import a list."

So I inserted a row at the top of column A in xlsx and wrote "Email Address" there. Copied again to clipboard and pasted into MailChimp. Get same error as above.

Tried next copying the A column and pasting into Notepad++. Wrote "Email Address" above the first email, and copied from Notepad++ copied to clipboard. Selected "Import contacts from .csv or .txt file" in Mailchimp and pasted again. Still get the same error: "You must have an email address column to import a list."

So what is MailChimp looking for?

Thanks for any help

Hi all,
Yesterday, I had a user receive over 9000 emails in one hour - they where all newsletter style emails (including many from Mailchimp) in many different languages.  The scary thing was that they all looked like legit subscriptions - headers looked legit etc.  The user is hosted on exchange 2010 and it didn't affect any of his colleagues.  Neither watchguard nor Xeams picked up on it and how I eventually got it under control was to increase the spam weighting of subscribe/welcome/subscription etc and then have them quarantined.  
Apparently he hasn't subscribed to any newsletters but has anyone ever had this happen to them and how did it start?
Cheers