Outlook Not Working? Fix Outlook Desktop & Web Issues

Microsoft Outlook is the backbone of business email, and when it stops working, productivity grinds to a halt. Whether Outlook won't open, won't send emails, keeps crashing, or won't sync, this guide has the fix. We cover Outlook desktop (part of Microsoft Office/365), the new Outlook for Windows, and Outlook.com (web version).

Fix 1: Start Outlook in Safe Mode

Safe Mode disables all add-ins and custom settings. If Outlook works in Safe Mode, an add-in is causing the problem:

If Outlook opens in Safe Mode, go to File → Options → Add-ins → Manage: COM Add-ins → Go — uncheck all add-ins, restart normally, then re-enable one at a time to find the culprit.

Fix 2: Repair Microsoft Office

1. Open Settings → Apps → Installed apps
2. Find Microsoft Office or Microsoft 365
3. Click the three dots → Modify
4. Select "Quick Repair" first — this fixes most issues in minutes
5. If Quick Repair doesn't work, run "Online Repair" (requires internet, takes longer but is more thorough)

Fix 3: Disable Work Offline Mode

In Outlook desktop, click the Send/Receive tab. If "Work Offline"is highlighted/pressed, click it to turn it off. When Work Offline is enabled, Outlook won't send or receive any emails — this is accidentally activated more often than you'd think.

Fix 4: Create a New Outlook Profile

A corrupted Outlook profile causes many issues — not opening, not syncing, or constant crashes:

1. Open Control Panel → Mail (Microsoft Outlook)
2. Click Show Profiles
3. Click Add → name it "New Profile"
4. Set up your email account in the new profile
5. Set the new profile as default: "Always use this profile" → select New Profile
6. Restart Outlook — it will use the fresh profile

Fix 5: Repair Outlook Data File (PST/OST)

Outlook stores emails in PST (POP accounts) or OST (IMAP/Exchange) files. If these get corrupted:

• For PST files: Use SCANPST.EXE (Inbox Repair Tool). Find it in: C:\Program Files\Microsoft Office\root\Office16\
• Run SCANPST → browse to your PST file → Start → Repair
• For OST files: Close Outlook → navigate to %localappdata%\Microsoft\Outlook\ → delete the .ost file → reopen Outlook — it will rebuild the OST from the server
• To find your data file location: Outlook → File → Account Settings → Data Files tab

Fix 6: Fix Outlook Not Sending Emails

1. Check your Outbox for stuck emails — open each one and try resending or delete and recreate
2. Make sure Work Offline is disabled (Send/Receive tab)
3. Verify SMTP settings: File → Account Settings → select account → Change → More Settings → Outgoing Server
4. Check "My outgoing server requires authentication"
5. Use port 587 with TLS encryption
6. If using Microsoft 365, try sending from outlook.office.com (web version) to confirm the account itself works

Fix 7: Fix Outlook Search

1. Go to File → Options → Search → Indexing Options
2. Make sure Microsoft Outlook is listed as an indexed location
3. Click Advanced → Rebuild — this rebuilds the search index from scratch
4. Wait for indexing to complete (can take 1-4 hours depending on mailbox size)
5. If still broken, repair Office installation (see Fix 2)

Fix 8: Fix Outlook Calendar Not Syncing

Calendar sync issues often affect Exchange/365 accounts. Fix: (1) Make sure the calendar is selected in the folder pane, (2) Send/Receive tab → Update Folder, (3) Check shared calendar permissions with your IT admin, (4) Remove and re-add the Exchange account, (5) If using Outlook.com, go to calendar.live.com to verify events exist server-side.

Fix 9: Outlook.com (Web) Issues

• Won't load: Clear browser cache, try Incognito/Private mode, try a different browser
• Slow: Disable browser extensions, especially ad blockers which can interfere
• Not receiving: Check Junk folder, check Focused vs. Other inbox tab, check rules (Settings → Rules)
• Can't sign in: Go to account.live.com for password reset and account recovery