OP here. For those thinking that Gmail MUST have valid reasons, and that we abusing the system in some way, consider... 1. We are registered with Gmail, Micros

OP here. For those thinking that Gmail MUST have valid reasons, and that we abusing the system in some way, consider... 1. We are registered with Gmail, Microsoft and Yahoo to provide feedback when someone marks our messages as spam (we DO do everything right). We get reports less than once a week, so if I've got my maths right, less than 0.002% of recipients think we're spammers. 1. Our two servers send around 10,000 messages a day, spread fairly evenly over time. That works out at three or four messages per server per minute. If we were spammers, we'd be ashamed of ourselves.