How to modify %email_values format in custom template

In the email, the standard value for %email_values is

field_name: field_value, e.g. Company: XYZ Corp.

I'd like it to be

field_name=field_value, e.g. Company=XYZ Corp.

How can I tweak the template to make that substitution?

I assume I'll need to use the str_replace command in the php template but, being a bit of a newb with respect to php, I don't know where to put it.

Thanks in advance for your help.

<?php

/**
 * @file
 * Customize the e-mails sent by Webform after successful submission.
 *
 * This file may be renamed "webform-mail-[nid].tpl.php" to target a
 * specific webform e-mail on your site. Or you can leave it
 * "webform-mail.tpl.php" to affect all webform e-mails on your site.
 *
 * Available variables:
 * - $node: The node object for this webform.
 * - $submission: The webform submission.
 * - $email: The entire e-mail configuration settings.
 * - $user: The current user submitting the form.
 * - $ip_address: The IP address of the user submitting the form.
 *
 * The $email['email'] variable can be used to send different e-mails to different users
 * when using the "default" e-mail template.
 */
?>
<?php print ($email['html'] ? '<p>' : '') . t('Submitted on %date'). ($email['html'] ? '</p>' : ''); ?>

<?php if ($user->uid): ?>
<?php print ($email['html'] ? '<p>' : '') . t('Submitted by user: %username') . ($email['html'] ? '</p>' : ''); ?>
<?php else: ?>
<?php print ($email['html'] ? '<p>' : '') . t('Submitted by anonymous user: [%ip_address]') . ($email['html'] ? '</p>' : ''); ?>
<?php endif; ?>

<?php print ($email['html'] ? '<p>' : '') . t('Submitted values are') . ':' . ($email['html'] ? '</p>' : ''); ?>

%email_values

<?php print ($email['html'] ? '<p>' : '') . t('The results of this submission may be viewed at:') . ($email['html'] ? '</p>' : '') ?>

<?php print ($email['html'] ? '<p>' : ''); ?>%submission_url<?php print ($email['html'] ? '</p>' : ''); ?>