Hi @Tricia ,
Welcome to our forum!
Does this issue occur in Outlook desktop client or Outlook for web?
And does this issue occur with other emails?
According to your description, i notice that you are trying to send emails with some photos. Please first check your internet connection: Make sure you have a stable internet connection and try sending the email again.
If the issue persists, in order to further confirm if the issue is related to the current email, it's suggested that you could try to create another email and send it to check if the issue persists.
If another email can be sent successfully, considering the impact of the photos, it's suggested that you could compress them before sending them to check if the problem exists.
Hope to help you!
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.