Email addresses used for SPAM

We’d just like to draw attention to the fact that a couple of our zero27 email addresses have been used in SPAM attacks.  It is a total nuisance for us – but is so easy for a spammer to do – simply put one of our email addresses in the “Reply-To” line of an email – result?  We are being swamped with “Message Undeliverables” into our mail boxes of the affected accounts.