reply email with data not working

[electricpet]

For each email that is sent in html format, the recipient can respond to the email by clicking on a link. For some reason or other, this code used to work, but has stopped recently... any ideas?
<p style="font-family: Calibri;" class="style8">
Respond to this email.<span style="">&nbsp; </span>Click<a
title="send order by email"
href="mailto:order@magneticsprings.com?subject=Water%20Order%20%5B%5BACCOUNT%5D%5D">
<b style="">here</b></a> to respond.</p>

This is what comes back as the subject line:

RE: Water Order [[ACCOUNT]]

an actual account number should show up!

[beiley]

Hi electricpet,

You don't want to encode the double square brackets in your HTML if you want the mail merge to work. Change:

%5B%5BACCOUNT%5D%5D

to

[[ACCOUNT]]

in your HTML file, and then the mail merge will work.

Mark