We frequently change clients MX records when they are ready to upgrade from ISP provided POP3 to Hosted Exchange. Usually the MX record change shows within a few minutes on MX tools website, and then within a few hours goes to all of the DNS servers, and its a done deal.
We moved a client last Friday from their ISP's mail (ISP also controls DNS for their web domain) to our system. The ISP made the correct MX changes on their site. MX tools website shows both of the new MX records and none of the old ones. Our work server, and a few other peoples email go to the new system. But everything else is still going to the ISPS email system. I figured enough time had not passed, so I have waited until today (4 Days) and still no change. How can I tell for 100% when this old record will expire and people will get the new IP? Is there a way to make this happen sooner?