I had the same request from a client today and this is what i did.
edited a couple of php's which will add an extra field in the settings page.
Add your additional email addresses to this new field seperated by comma for each address.
1. Open: admin/includes/settings/index.php
Find:
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<tr>
<td width="30%" class="tdText"><strong><?php echo $lang['admin']['settings']['email_address'];?></strong><br />
<?php echo $lang['admin']['settings']['email_address_desc'];?></td>
<td align="left"><input type="text" size="35" class="textbox" name="config[masterEmail]" value="<?php echo $config['masterEmail']; ?>" /></td>
</tr>
*****************************************************************************
*****************************************************************************
Add after:
*****************************************************************************
// added by anynet to email orders to list.
<tr>
<td width="30%" class="tdText"><strong>Optional Sendto emails</strong><br />
(This is used to add additional email addresses to send order info to) Comma seperated.</td>
<td align="left"><input type="text" size="35" class="textbox" name="config[masterEmailTo]" value="<?php echo $config['masterEmailTo']; ?>" /></td>
</tr>
*****************************************************************************
*****************************************************************************
Save file.
2. Open: includes/content/gateway.inc.php
Find:
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$send = $mail->send(array($config['masterEmail']), $config['mailMethod']);
*****************************************************************************
*****************************************************************************
Add after:
*****************************************************************************
// added by anynet to email orders to list.
$send = $mail->send(array($config['masterEmailTo']), $config['mailMethod']);
*****************************************************************************
*****************************************************************************
Save file.
EOF
Hope this helps