How to Fix Outlook Emails Stuck in the Outbox

You hit Send, but your email just sits in the Outbox. It doesn't send, or it sends hours later. This isn't just a temporary glitch - it's one of the most common (and frustrating) Outlook problems. You may try to resend the email, restart Outlook, or even reboot your PC, only to find the message is still stuck.

This typically happens when:

  • Your internet connection drops or reconnects mid-send
  • The email has a large attachment that Outlook struggles to process
  • Outlook is working offline without your knowledge
  • An antivirus or third-party plugin is interfering with the send process

Over time, this leads to users hitting "Send" multiple times, getting duplicate messages, or worse - thinking the email went out when it didn't. It also results in delays, confusion with recipients, and often embarrassment or missed deadlines.

Why This Happens - Common Root Causes

  • Offline mode: Outlook toggles to offline without clearly indicating it
  • Large attachments: Files over 10MB can stall send operations, especially on slower networks
  • Antivirus interference: Some security tools scan outgoing mail, causing unexpected timeouts or stalls
  • Corrupted mail profile or OST/PST file: Local storage problems can block mail from leaving the queue, especially in long-standing profiles
  • Add-ins or sync tools: Especially backup utilities, PST archivers, calendar sharing tools, or CRM plugins

Users often describe this issue as "Outlook won't send emails," "email stuck in outbox not sending," or "message sending takes forever." These are all symptoms of Outlook email sending being blocked - either by something in its environment or by external processes.

How to Fix It

Try the following solutions one-by-one.

Check Your Connection and Outlook Offline Mode

  • Look at the bottom bar of Outlook. If it says Working Offline, go to Send/Receive > Work Offline to toggle back online.
  • If Outlook is "Trying to connect..." for a long time, restart it and check your internet.

Try Safe Mode

  • Run outlook.exe /safe from the Windows Run dialog
  • If the email sends in Safe Mode, one of your add-ins is the culprit.

Reduce Attachment Size

  • Compress attachments into ZIP files
  • Use OneDrive, SharePoint, or Dropbox links
  • Split attachments across multiple emails if needed

Rebuild Your OST File or Fix your PST file

A corrupted OST or PST file is a common cause of all sorts of Outlook issues. Follow the instructions in the first two sections of this article to fix your mail files.

Repair or Recreate Your Outlook Profile

  • Open the Windows Control Panel
  • Type "mail" in the Search box in the upper-right
  • Click "Mail" then "Show Profiles"
  • Add a new profile, configure your account, and test sending

Disable Antivirus Email Scanning Temporarily

  • Temporarily turn off email scanning in your antivirus settings
  • Try resending the stuck message
  • Re-enable scanning afterward

Manually Force Send/Receive

  • Press F9 or go to Send/Receive > Send All

Use Outlook Web as a workaround

  • Log in to Outlook Web Access (OWA)
  • Try resending or recreating the message from there

In Closing

When emails get stuck in the Outbox, in most cases, it's a local glitch, not a server failure. Outlook was built to send - if it isn't, it's trying to tell you something. With a few quick checks - offline mode, attachments, mail file (OST, PST) and profile health - you can get mail flowing again and avoid embarrassing delays.