Outlook Not Sending Emails on Windows 11? Fix Guide

You click Send, but emails sit in Outbox and never leave — or Outlook throws a send/receive error. This is especially common on Windows 11 due to the new Outlook app changes and Microsoft's authentication updates. Here's how to fix every common scenario.

Fix 1: Disable Work Offline Mode

The simplest cause: Open Outlook → go to the Send/Receive tab → check if "Work Offline" is highlighted/active. If yes, click it to disable. The status bar at the bottom should change from "Working Offline" to "Connected."

Fix 2: Clear Stuck Emails from Outbox

1. Go to Send/Receive tab → Work Offline (enable it temporarily)
2. Open the Outbox folder
3. Open each stuck email → either move it to Drafts or delete it
4. Go back to Send/Receive → click Work Offline to go back online
5. Re-send from Drafts if needed

Fix 3: Check SMTP Settings

Incorrect outgoing server settings cause most send failures:

1. Open File → Account Settings → Account Settings
2. Select your account → click Change
3. Click More Settings → Outgoing Server
4. Ensure "My outgoing server requires authentication" is checked
5. Go to Advanced tab → verify:

Fix 4: Re-authenticate Your Account

1. Close Outlook completely
2. Open Control Panel → Credential Manager → Windows Credentials
3. Remove any entries related to Outlook, Office, or MicrosoftOffice
4. Open Outlook — it will prompt for your password again
5. Enter your current password (or app password if using 2FA)

Fix 5: Disable Antivirus Email Scanning

Some antivirus programs (Norton, Avast, Kaspersky) scan outgoing emails and can block them. Open your antivirus → find Email Protection or Mail Shield settings → temporarily disable outgoing email scanning. Try sending again. If it works, add Outlook to the antivirus exclusion list.

Fix 6: Check Attachment Size

• Microsoft 365/Outlook.com: 25 MB attachment limit per email
• Gmail (via Outlook): 25 MB total including email body
• Corporate Exchange: Often set to 10-20 MB by your IT admin
• For large files, use OneDrive sharing instead — Outlook has a built-in "Upload to OneDrive" button
• If a large email is stuck in Outbox, it may be blocking smaller emails behind it

Fix 7: Repair Outlook Data File

1. Close Outlook completely
2. Navigate to: C:\Program Files\Microsoft Office\root\Office16
3. Run SCANPST.EXE (Inbox Repair Tool)
4. Browse to your Outlook data file (.ost or .pst)
5. Click Start to scan
6. If errors found, click Repair
7. Open Outlook and try sending again

Fix 8: Create New Outlook Profile

If nothing else works, the Outlook profile may be corrupted:

1. Close Outlook
2. Open Control Panel → Mail → Show Profiles
3. Click Add → name it (e.g., "New Profile")
4. Set up your email account
5. Set the new profile as "Always use this profile"
6. Open Outlook — it will use the fresh profile with clean settings