Emails to me are getting bounced

I send an average of 2-4 emails a day from my godaddy email account. I learned from someone trying to email me that their emails to me have been bouncing back to them with this error message:


Remote-MTA: dns;
Diagnostic-Code: smtp; 554 bizsmtp has been blocked for the day, for attempting to mail too many invalid recipients. IB113

 Can someone explain to me what this means? It seems like it's saying I'm sending too much email and to "invalid" recipients, but like I say, I send only a few emails a day to recipients who are known to me.