I am currently testing the free business plan with a view to upgrading to a paid plan once I am happy the core mail functionality is what I need for circa 6 users. I have a hosted domain but as multiple domains can't be hosted on the free plan, I am trying to set up 'Send Mail As' addresses. 

Although I have been through the required process of adding a new 'From' e-mail address and then verifying via the code that is e-mailed, I am not presented with the option of choosing that additional address to send from when writing a new e-mail. I tested a personal free Zoho plan recently (rather than a business one) and it worked without issue so I am not sure why it is not working this time.

Have I missed something fundamental?

Many thanks

Andrew