TSGL: Old Undelivered Email

[Mike Ferrell]

In July of last year I corresponded with Echo, a mfg of weed wackers.  My issue was resolved and all is well.  At that time, I replied via email offering them a compliment for their exemplary service.  However, 6 months later, I have just started receiving the following message, 3 copies, daily.  Apparently, my last email to them in July has not delivered and I keep getting this Postfix message.  The message I receive is below.  I tried sending an email to <postmaster> as instructed, but that address is not recognized.  Any ideas on how to stop this?  It's not a big issue,  ... just getting tired of the messages.
Mike

This is the Postfix program at host utilnj01.rightnowtech.com.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to <postmaster>

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

The Postfix program