After an export of your contacts from your contacts application you have used so far you can import the contacts into the mail.com Contacts.
If you previously used a different program for your addresses, you do not have to re-enter your collection of addresses. You can copy the data to your mail.com Contacts in just a few steps. Click the wrench icon at the top right and then click Import Contacts and follow the instructions. Detailed instructions for the individual applications are available on a various websites: