Please note that this will not be possible as in Free mail service we only provide two mail accounts with 100 MB mailbox space. However clients are free to add forward only accounts of which we allow 10 such accounts.
For more information you may refer to the following KB article: http://support.mailhostbox.com/email-administrators-guide/add-forward-only-email-accounts
If the client would like to associate a 3rd account with the same domain name, then we would advice the clients to migrate from Free mail service to Business mail service. Clients will have to ensure that the following steps have been covered on their end prior to migration.
1. Ensure that contacts, signatures and other settings (vacation notice,forwards etc.,) are backed up for the accounts.
2. Ensure mail backup has taken place, by setting an email client on the clients system with POP settings and downloading the mails to their system for the accounts. Clients can use the following KB articles to help them achieve the same.
URL 1:How do I backup my emails on my personal computer?
URL 2: http://sibername.com/tutorial/how-do-i-take-a-local-backup-of-my-email-in-outlook-2010/
URL 3: http://support.mailhostbox.com/email-users-guide/configure-your-desktop-client-send-and-receive-email
3. Once this has taken place, then the client can simply place an order for business mails, depending upon the number of accounts they require and switch to business mails, which will allow them and upgrade in mailbox space (5GB) and other advanced features as compared to free mail service.
4. Post this once the accounts are created on Business mails, the clients can reference the below article on how to sync mails between two accounts using their email client. This will ensure that the new account will have all their mails.
Hope the information provided helps you. Feel free to get back to us if you require any further assistance or support from our end.