Using classic Outlook for Windows in business environments
Close Outlook completely, reopen it from the Windows Start menu, and then manually trigger Send/Receive to retry the unsent messages.
Restart and resend
- In Outlook, select File → Exit.
- Wait about 10 seconds.
- Select Start, type Outlook, and open Outlook (classic).
- Select Send/Receive → Send/Receive All Folders, or press F9.
- Check whether the exclamation mark disappears and the message leaves Outbox.
If the messages still will not send
- Check Outlook’s connection status
- Look at the bottom of the Outlook window.
- If it says Working Offline, Disconnected, or Trying to connect, select Send/Receive → Work Offline once to return Outlook to online mode.
- Open the stuck message and select Send again.^1^
- Remove a message blocking the Outbox
- Open Outbox.
- Start with the oldest message.
- If it has a large attachment—particularly one larger than 20 MB—remove or reduce the attachment, and then resend it. One oversized message can also block messages behind it.^1^
- Check for a changed password
- If the email account password was recently changed through the provider’s website, update the saved password in Outlook as well.^2^
Test Outlook without add-ins
If Outlook is connected and the Outbox is not blocked:
- Close Outlook.
- Press Windows logo key + R.
- Enter:
outlook.exe /safe - Select OK, open the normal profile, and send a small test message without an attachment.
If sending works in Safe Mode, an Outlook add-in is likely interfering. In Outlook Safe Mode, go to File → Options → Add-ins, select COM Add-ins → Go, disable the add-ins, and then restart Outlook normally.^3^
If none of these steps works, run Microsoft’s Classic Outlook troubleshooters. They apply to classic Outlook, not new Outlook for Windows.^4^
References