There are various reasons so that your email not send through Outlook account:-
1. Send Folder Open.
2. All Messages in the folder should be deleted.
3. Exit your Outlook account.
4.Restart your Outlook account.
5. If problem is resolved, Try sending an email to see
Read more here:- https://www.datarecovo.com/unable-to-send-emails-from-ms-outlook/
