Bounce backs and Error Messages!!

We are emailing people we have had no problem emailing before and now we are told they don't receive our emails and we have gotten "permanent errors" bounce back emails. This is the 3rd time we've had this with homestead. We have even canceled the service with homestead for some time and recently sign on again after being told the servers were up a running great. We run a business and this is unacceptable. We have even gotten emails bounced back saying  it has been 4 hours since the email was sent but was never delivered.