Thank you for reaching out to the Constant Contact Community. It's my pleasure to assist you today.
That's a great question. While you are in your initial 60 day trial, there are some limitations. One of them is that you can only send to 100 contacts, if your lists have more than that, they will be greyed out and you won't be able to send to them. You can create a list of 100 contacts, which it will let you select and send. I hope this helps. Please feel free to reach out should you need anything else.
Thank you for choosing Constant Contact. Have a great day!