I developed a website for a friend of mine to replace his current 'all inclusive' provider (website creation, updating, web hosting, email hosting).

I've already paid for a hosting service which currently houses the website which I have created. I need to cancel the previous service provider to get the domain migrated to the new host, however I will still need to transfer or recreate all of the email addresses that everyone in his company had previously. Is there an easy way migrate email accounts (still linked to the same domain) while migrating to a different host? Will any methods allow all users to retain their archived emails and folder structures? What is the process to do so.

Because the current provider is a rather large website development and hosting company, I will have limited access to the data they have stored.

As you can probably tell, my knowledge in this area is very limited - any/all suggestions you may have would be greatly appreciated.

Thanks in advance.

-Jack