You can check the messages you've sent in the message inbox of your Peatix account.

After signing in, click the mail icon in the top right corner to open your inbox, then click on [SENT].  

You can search for messages by username or filter them by event or group.

* The maximum number of messages that can be sent at once is 100. If you need to send messages to more than 100 attendees, the system will divide them into multiple batches. As a result, if you send messages to more than 100 attendees in one go, the messages will appear as separate entries in the "SENT" section.