Spam on customer Record message tab

We have a few customer records that have 1000+ spam messages on the messages tab.  New messages are added every day.  The messages are all from different email addresses but the recipient is the same employee email address every time.  That email address doesn't exist anymore (and hasn't for some time).

I suspect that the spammers got ahold of the long netsuite email address that's used to track emails between customers and us.  Support doesn't seem to understand this.  They keep telling us that we need to fix our email server but our servers are not the cause of this, nor are the messages coming to our email in-boxes, just to the netsuite customer record.