Not necessarily — it depends on how you choose to handle DNS.
You can keep your DNS with your current provider — often the company you originally registered the domain with — and simply point the CNAME for your domain at your Pagely instance. Nothing else needs to change.
Alternatively, if you allow Pagely to manage your DNS — to take advantage of the many benefits of PressDNS — you will need to set up your MX records with us to ensure your Gmail continues to function correctly. We have a one-click setup for Google Apps via our interface so it is a straightforward process.
Keeping your current DNS provider if often the simplest option to start, but if you would like to completely get away from a previous provider, you can have Pagely manage your DNS for you — we provide this service free of charge with your hosting plan.
Our Support team helps with migrations like this every day.