In many cases, you won’t have to do anything. If you have Gmail or another “forever” email you’ll continue to receive your email.
If your email is through your previous ISP you may be able to keep that too. Comcast, for example, has a policy in place that allows
you to keep your email accounts even if you do not purchase their service.
From their website:
As a former XFINITY customer, you can still use your Comcast.net email address if you logged into your account in the 90 days prior to disconnecting your service. Your email account will remain active as long as you access it at least once every nine months.
For additional information: Using Comcast Email if You’ve Disconnected Your Service
You may review the document below for additional information about switching or transferring email addresses. As part of your Whip City Fiber service, you may request five free email accounts (your firstname.lastname@example.org) from email@example.com
Email Transfer (PDF)