On the left side of the page click on 'Hosting Services' then underneath it select 'Manage Exchange' . Select the correct Organization Name and hit 'Mailboxes' to continue.
You will see Mailboxes of your domain , click 'Add Mailbox'
You must enter the required fields below
Mailbox Name: email@example.com
Password : create a password that you can always remember
Confirm Password: retype your password
General profile : Click 'Configure'
First Name: enter your first name
Last Name: enter your last name
Display Name: enter your display name you wanted
Scroll down and click 'Configure' for Advance Settings
Uncheck box for unlimited Mailbox Size :please make sure this value is not 0
Outgoing Message Size Limit: please make sure this value is not 0
Incoming Message Size Limit: please make sure this value is not 0
click add mailbox
You will see "Success Mailbox created successfully"
You will see Mailboxes of your domain , select the right email address you want to edit and hit 'Edit Mailbox'
Click 'Advanced Properties' then put a check marks for IMAP, POP ,OWA/HTTP and MAPI and click 'Update Mailbox' after you verified all entries are correct.
You will see Success:Mailbox updated successfully.
Mailbox Size (MB): this may depend on your plan
Outgoing Message Size Limit : this may depend on your plan
Incoming Message Size Limit : this may depend on your plan
Go back to Mailboxes of your domain and select the email address you want to enable, select 'Active Sync Settings'.
Verify your Display Name and select 'Enabled' for Active Sync Status. ,then choose 'Enabled' the click 'Save Settings'.