You can see your Sent Messages in one of two places, depending on how they were sent originally.

See your Sent Broadcasts

...

• The Broadcasts tab of the Messaging App displays broadcast messages that were sent to multiple contacts at once. The message is shown in the Message column.

See the messages sent to an individual Contact

• The Conversations tab of the Messaging App displays your conversation history with each contact. This includes:

  • Individual messages that were sent to this contact

  • Messages sent to your organisation from this contact

  • Bulk Messages in which this contact was a recipient

...