Can't compose email with my new mail account

Can't compose email with my new mail account

Hi there,
I have set up the Email Hosting with Zoho yesterday and I have done the verification, added users and so on...
I can see the list of users in my Mail Accounts in Control Panel but,
I can't see them in the 'From' list when composing mail in Mail Composer.
The only email address I can choose is XXXX@zoho.com
What's the problem?