LiveAgent trial account has the following email limitations:
possibility to send max 5 emails in 5 minutes
possibility to send max 30 emails in 1 hour
email can contains max 5 recipients (To + Cc + Bcc)
If you feel you need more about it, do not hesitate to upgrade your current plan in Account section in LiveAgent Dashboard.
Thank you for trusting LiveAgent. If you have any further question, feel free to get in touch via email or chat.