An important part of our spam-fighting strategy is the use of a "greylist". The idea with grey-listing is that when the server receives mail from an unknown sender, it responds with a "try again later" notice. According to industry-standard email specifications, mail servers are supposed to heed these messages and attempt a re-send. And almost 100 percent of them do. But spammers typically don't, and therefore the spam never gets through. After a certain number of successful re-sends, a sender is automatically added to a whitelist and subsequently their emails are accepted immediately. It's a great system, but it does cause delays initially. So if someone says they "just sent you an email", you might not get it right away. If you would prefer to opt out of the greylist feature, please submit a support request.
