app/Template/comment_mail/create.php

<div class="page-header">
    <h2><?= t('Create and send a comment by email') ?></h2>
</div>
<form method="post" action="<?= $this->url->href('CommentMailController', 'save', array('task_id' => $task['id'])) ?>" autocomplete="off" class="js-mail-form">
    <?= $this->form->csrf() ?>
    <?= $this->form->hidden('task_id', $values) ?>
    <?= $this->form->hidden('user_id', $values) ?>

    <?= $this->form->label(t('Email'), 'emails') ?>
    <?= $this->form->text('emails', $values, $errors, array('autofocus', 'required', 'tabindex="1"')) ?>

    <?php if (! empty($members)): ?>
        <div class="dropdown">
            <a href="#" class="dropdown-menu dropdown-menu-link-icon"><i class="fa fa-address-card-o"></i><i class="fa fa-caret-down"></i></a>
            <ul>
                <?php foreach ($members as $member): ?>
                    <li data-email="<?= $this->text->e($member['email']) ?>" class="js-autocomplete-email">
                        <?= $this->text->e($this->user->getFullname($member)) ?>
                    </li>
                <?php endforeach ?>
            </ul>
        </div>
    <?php endif ?>

    <?= $this->form->label(t('Subject'), 'subject') ?>
    <?= $this->form->text('subject', $values, $errors, array('required', 'tabindex="2"')) ?>

    <?php if (! empty($project['predefined_email_subjects'])): ?>
        <div class="dropdown">
            <a href="#" class="dropdown-menu dropdown-menu-link-icon"><i class="fa fa-archive"></i><i class="fa fa-caret-down"></i></a>
            <ul>
                <?php foreach (explode("\r\n", trim($project['predefined_email_subjects'])) as $subject): ?>
                    <?php $subject = trim($subject); ?>

                    <?php if (! empty($subject)): ?>
                        <li data-subject="<?= $this->text->e($subject) ?>" class="js-autocomplete-subject">
                            <?= $this->text->e($subject) ?>
                        </li>
                    <?php endif ?>
                <?php endforeach ?>
            </ul>
        </div>
    <?php endif ?>

    <?= $this->form->textEditor('comment', $values, $errors, array('required' => true, 'tabindex' => 3, 'aria-label' => t('New comment'))) ?>

    <?= $this->modal->submitButtons(array(
        'submitLabel' => t('Send by email'),
        'tabindex'    => 4,
    )) ?>
</form>