Hi @Treve Jenkyn
Welcome to our forum!
Do you mean you sent merge emails but couldn't find them? If so, it's a good idea to review your sent messages or use the search function to search for related sent message content in your Outlook.
If not, may I understand you composed merge messages but did not know how to send them? In this case, according to my research, you can find the Send Mail button in the diagram: More information: Video: Mail merge - Microsoft Support
Hope it helps!
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our [documentation] to enable e-mail notifications if you want to receive the related email notification for this thread.