It is available while you are still in the evaluation mode.
Create a message, and add all the recipients. When you are ready to send, click the down-arrow in the Send button and choose Send as Mass Mail.
This will send a message to each recipient separately. If you have added variables in the message, they will be replaced from data from the Contact details you have for that recipient.
So you may have:
Hello {Given Name}
That will be replaced by:
Hello Michael (or whatever the contact’s first name is)
So an individual personalized message to each recipient.