eg. GoDaddy
1) Login into your account on GoDaddy

2) Select “Domains” on Top Menu and then “Manage My Domains” on dropped down menu

3) Select your domain. Which’s emails you want host on ShazzleMail

4) On domain screen select DNS and Edit

5) Then remove all records in MX section and Add new one
Priority: 0
Host: @
Points To: mail3.shazzlemail.com
TTL: 1 Hour

6) And then save changes

Changes will be applied up to 48 hours as GoDaddy saying. If you had no MX records before – it
could be applied in several minutes.