I help one customer to transfer his account/domain to our host domain. I create his account/domain on our host server. And also i set up serveral email accounts. Then i asked his provider to switch DNS server to our server. I know after swtiching, i should wait from one to three days. But the interesting thing is that i can send/receive email even when i use "whois" and it still display the old name server. Any idea about this?