When you perform a domain transfer, you move only the domain itself. Email is content that remains with your previous provider/hoster.
If you have an agreement with your previous hoster that they will continue to manage your email, you can connect your domain to that hoster via MX record. If there is no agreement, you will need a mail hosting package with us, for example. With this you can create new email addresses.
Note that you have to set up each email address again. The email box is thus new and empty. There will be an interruption while the new email addresses are being set up. Additionally, it may be necessary to back up the contents of the previous email box.
All hosting offers are available in the personal customer area under the menu item Hosting or under Offers.