When a message gets stuck in your Outbox, the most likely cause is one or many emails that contain large attachments trying to upload to Exchange Online mail services. If Outlook is closed or a device starts sleep mode while large email messages are being uploaded, additional issues with syncing messages can develop.
To have Outlook try sending messages that are stuck, try the steps below.
- In Outlook, click the Send/Receive tab, then click Work Offline.
- In the Navigation Pane and click Outbox.
- From here you can:
- Drag the message from your Outbox folder to your Drafts folder. Open the message now within the Drafts folder and delete the attachment it contains. Attempt to add a smaller version of the attachment. When the message is ready, click Send.
- Delete the message from your Outbox folder. Select the message and press Delete. You will need to compose a new message with attachment to send.
If an error tells you Outlook is trying to transmit the message, close Outlook. It may take a few moments to exit.
Note: If Outlook doesn’t close, press Ctrl + Alt + Delete and click Start Task Manager. In Task Manager, click the Processes tab, scroll down to outlook.exe, and click End Process.
- After Outlook closes, start it again and repeat steps 2-3.
After you remove the attachment, click Send/Receive > Work Offline to deselect the button and resume working online.
Note: Messages also get stuck in the Outbox when you click Send but you’re not connected. Click Send/Receive and look at the Work Offline button. If it’s blue, you’re disconnected. Click it to connect (the button turns white) and click Send All.
If you continue to experience issues with Outlook, please submit a support request for Real World Technology Solutions support team to investigate further. Be sure to include as much detail as possible about Outlook's issue including if the issue consistently occurs, the times the issues tend to occur, the size of your mailbox and information about your internet connection and usage.
If unsure about the steps to perform or would like Real World Technology Solutions support team members to assist and perform - please submit a support request for remote support session.