Migrate email account from existing ISP to a new one

My current email set up isn’t quite working for me and I need some help moving over to a new ISP. I need to migrate all of the content, emails, and folders that I currently have in my existing account - which is over 5GB of data - to the new account that I am setting up. I do not need any additional services such as email backup or spam filter setup. The freelancer I choose will be responsible for handling the migration from my current setup to the new system and making sure that all my emails, data, and folders come along with me too. Need to keep the same address, as well as have it interface though MS Outlook 2013