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10 Tech How-To

Outlook Crashing When Sending Emails: Fix

Guide 10-29413 · Updated · Step by step

Outlook crashing the moment you hit Send is a frustrating problem that usually points to a corrupted add-in, a damaged profile, or a conflict with the email account settings. This guide walks you through the most effective fixes, from quick workarounds to deeper repairs, so you can get back to sending emails without losing your data.

What You’ll Need

  • Access to your Windows or Mac computer where Outlook is installed
  • Your email account credentials (password) in case you need to recreate your profile
  • Administrator rights on the computer (for some steps like repairing Office)
  • Optional: a backup of your Outlook data file (.pst or .olm) if you plan to recreate your profile

Step-by-Step

1. Start Outlook in Safe Mode

Safe Mode disables all add-ins and customizations, which are the most common cause of crashes. On Windows, press Win + R, type outlook.exe /safe, and press Enter. On Mac, hold the Option key while launching Outlook. If Outlook works fine in Safe Mode, an add-in is the culprit. If it still crashes, skip to Step 4.

2. Disable Problematic Add-Ins

While in Safe Mode, go to File > Options > Add-Ins. At the bottom, next to “Manage,” select COM Add-ins and click Go. Uncheck all add-ins (especially third-party ones like antivirus integrations, PDF tools, or CRM plugins), then click OK and restart Outlook normally. If it stops crashing, re-enable add-ins one by one to find the offender. Once identified, keep it disabled or check for an update.

3. Repair Your Outlook Data File

A corrupted mailbox or data file can cause crashes when sending. Close Outlook, then locate the Inbox Repair Tool (scanpst.exe). On Windows, it’s usually in C:\Program Files\Microsoft Office\root\Office16 or C:\Program Files (x86)\Microsoft Office\root\Office16. Run it, browse to your .pst file (find it via File > Account Settings > Data Files in Outlook), and click Start. Let it scan and repair any errors. On Mac, use the Mailbox Rebuild feature under Window > Mailbox Rebuild.

4. Create a New Outlook Profile

If add-ins and data files aren’t the issue, your profile may be corrupted. Open Control Panel > Mail (on Windows) and click Show Profiles. Select your profile and click Remove (this does not delete your emails if they’re on the server). Then click Add to create a new profile, enter your email account, and set it as the default. Launch Outlook with the new profile. If it works, you can import your old .pst file via File > Open & Export > Import/Export.

5. Repair Office Installation

A damaged Office installation can cause Outlook to crash. On Windows, go to Settings > Apps > Apps & features, find Microsoft Office, click Modify, and choose Quick Repair (or Online Repair if that fails). On Mac, run the Microsoft AutoUpdate tool to reinstall components. This process may take a few minutes but often resolves underlying issues.

6. Disable Hardware Graphics Acceleration

Sometimes Outlook’s rendering engine conflicts with your graphics driver. Go to File > Options &strong> Advanced, scroll to “Display,” and check Disable hardware graphics acceleration. Restart Outlook and test sending an email.

7. Check for Conflicting Antivirus or Firewall

Some security software scans outgoing emails and can cause Outlook to hang or crash. Temporarily disable your antivirus real-time scanning (or the email scanning component) and try sending a test email. If it works, add Outlook to the exclusion list or contact your antivirus vendor for instructions. Remember to re-enable protection after testing.

8. Update Outlook and Windows

Ensure Outlook and your operating system are fully updated. On Windows, go to File > Office Account > Update Options > Update Now. Also check Windows Update for pending updates. On Mac, use the App Store or Microsoft AutoUpdate. Updates often include fixes for known crash bugs.

Common Mistakes

  • Skipping Safe Mode: Jumping straight to reinstalling Office when a simple add-in disable would fix it.
  • Not backing up before repairing: Running scanpst or recreating a profile without a backup can lead to data loss if something goes wrong.
  • Disabling all add-ins permanently: You might lose functionality you need. Instead, isolate the specific add-in.
  • Forgetting to restart after changes: Many fixes require a full restart of Outlook, not just closing the window.

Tips

  • Keep your add-ins minimal—only install those you actually use.
  • Regularly compact your PST file (via Account Settings > Data Files > Settings > Compact) to reduce corruption risk.
  • If you use a large mailbox, consider archiving old emails to keep the main file smaller.
  • Use the “Send/Receive” manual option (F9) occasionally to catch issues before they become crashes.

Troubleshooting

If the steps above don’t resolve the issue, try these additional checks:

  • Check for large attachments: A file over the server limit can cause a crash. Try sending a plain text email without attachments to test.
  • Create a new email account temporarily: If the crash only happens with one account, the account settings may be corrupted. Delete and re-add the account in Outlook.
  • Look at Event Viewer: On Windows, open Event Viewer (eventvwr.msc), go to Windows Logs > Application, and look for errors with source “Outlook” or “Application Error.” The faulting module name (e.g., “outlook.exe” or a DLL) can point to the culprit.
  • Run Microsoft Support and Recovery Assistant: Microsoft’s free tool can diagnose and fix Outlook issues automatically. Download it from the official Microsoft site and follow the prompts.
  • Check for conflicting email signatures: A corrupted signature can crash Outlook when sending. Go to File > Options > Mail > Signatures and remove any custom signatures, then test.

Frequently Asked Questions

Why does Outlook crash only when I send emails, not when reading?

Sending triggers more processes—attachments, signatures, spell check, and server communication. A problem in any of these, like a corrupt signature or a faulty add-in that hooks into the send event, can cause a crash.

Will I lose my emails if I create a new profile?

No, as long as your emails are stored on the server (IMAP or Exchange) or you have a backup of your .pst file. POP3 accounts store emails locally, so back up the .pst before removing the profile.

How do I know if an add-in is causing the crash?

If Outlook works in Safe Mode (with add-ins disabled), then an add-in is the cause. Re-enable them one by one to identify the culprit.

Can a large mailbox cause Outlook to crash when sending?

Yes, a very large PST file (over 20 GB) can become unstable and cause crashes. Archiving or compacting the file can help.

Is there a way to send emails without Outlook while I fix it?

Yes, you can use the web version of your email provider (like Outlook.com or Gmail) to send urgent emails while you troubleshoot.

What should I do if none of the steps work?

As a last resort, uninstall and reinstall Microsoft Office completely. Before doing so, back up your data files. If the problem persists after a clean install, it may be a system-level issue—consider contacting Microsoft Support.

Related

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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