Important: Switching requires coordination.
Special care must be taken to coordinate things if you are already using the domain for email.
When you change the domain (technically, when you change the 'MX' records), the email will start arriving at our servers. Your email client may still be looking for the email where it was and it will need to be reconfigured.
#1: Establishing the email accounts
Our server will not at first have the the accounts of the prior email server. The accounts can be reestablished but will have newly assigned passwords.
#2: Saving your email
Our server will not have the email of the prior email server. Any email on the old server will stay there. Most email clients bring the email into your local PC, but web based email does not and even installed email clients such as Microsoft Outlook can be set to leave the email on the server.
When the domain or the "MX" records are changed it takes the internet up to 4 days to handle the change. The switchover happens erratically - some machines might start using the new information nearly instantly, while others are still sending to the old machine 3 days later. In practice, we have seen the switchover take about a day, but the internet standard allows 4 days. During this time some email might go to the old server and some to the new one.
Note: The process is complicated but can be done successfully.