Eliminate event attributes from email forms.

themes/bootstrap3/templates/Helpers/email-form-fields.phtml

 <div class="form-group">
   <label class="control-label" for="email_to"><?=$this->transEsc('To')?>:</label>
-  <input type="<?=$this->maxRecipients != 1 ? 'text' : 'email'?>" id="email_to" class="form-control" oninvalid="$('#modal .fa-spinner').remove()" name="to" value="<?=isset($this->to) ? $this->to : ''?>"/>
+  <input type="<?=$this->maxRecipients != 1 ? 'text' : 'email'?>" id="email_to" class="form-control" name="to" value="<?=isset($this->to) ? $this->to : ''?>"/>
   <?php if ($this->maxRecipients != 1): ?>
     <br />
     <?=$this->transEsc('email_multiple_recipients_note')?>
@@ -12,13 +12,13 @@
 <?php if (!$this->disableFrom): ?>
   <div class="form-group">
     <label class="control-label" for="email_from"><?=$this->transEsc('From')?>:</label>
-    <input type="email" id="email_from" oninvalid="$('#modal .fa-spinner').remove()" name="from" value="<?=isset($this->from) ? $this->from : ''?>" size="40" class="form-control"/>
+    <input type="email" id="email_from" name="from" value="<?=isset($this->from) ? $this->from : ''?>" size="40" class="form-control"/>
   </div>
 <?php endif; ?>
 <?php if ($this->editableSubject): ?>
   <div class="form-group">
     <label class="control-label" for="email_subject"><?=$this->transEsc('email_subject')?>:</label>
-    <input type="text" id="email_subject" oninvalid="$('#modal .fa-spinner').remove()" name="subject" value="<?=isset($this->subject) ? $this->subject : ''?>" size="40" class="form-control"/>
+    <input type="text" id="email_subject" name="subject" value="<?=isset($this->subject) ? $this->subject : ''?>" size="40" class="form-control"/>
   </div>
 <?php endif; ?>
 <div class="form-group">
@@ -38,3 +38,10 @@
 <div class="form-group">
   <input type="submit" class="btn btn-primary" name="submit" value="<?=$this->transEsc('Send')?>"/>
 </div>
+<?php $emailFormScript = <<<'JS'
+    $('#email_to, #email_from, #email_subject').on('invalid', function($e) {
+        $('#modal .fa-spinner').remove();
+    });
+JS;
+?>
+<?=$this->inlineScript(\Laminas\View\Helper\HeadScript::SCRIPT, $emailFormScript, 'SET');