Summary

This guide helps you troubleshoot and resolve: Email delivery delays. Follow the steps below to fix the issue.

Common Causes

Email Delivery Delays - What to Do

Overview

Emails taking too long to arrive? This guide helps diagnose and fix email delivery delays in Microsoft 365.

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Normal Delivery Times

• Internal emails: Usually instant (seconds to 1-2 minutes)
• External emails: Typically 1-5 minutes
• High volume periods: May take longer during business hours

Warning signs: Emails taking 15+ minutes consistently

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Quick Checks

1. Check Your Send/Receive

1. In Outlook, click Send/Receive tab

2. Click Send All to force delivery

3. Check if emails are stuck in Outbox

2. Check Outbox for Stuck Emails

1. Look at your Outbox folder

2. If emails are stuck there:

• Double-click to open
• Click Send button
• Or check for "Send" errors

3. Check Your Connection

• Try loading a website
• If internet is slow, email will delay too

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Common Causes & Fixes

1. Large Attachments

Problem: Files over 25MB queue slowly

Solution: Use OneDrive to share large files, then send link

2. Outlook Not Running

Problem: Emails queue until Outlook connects

Solution: Keep Outlook running or use Outlook on the web

3. Scheduled Send

Problem: You accidentally scheduled email for later

Solution: Check email properties for scheduled time

4. Mail Server Congestion

Problem: High email volume at Microsoft

Solution: Wait and retry later, or use Outlook on web

5. Recipient Server Issues

Problem: Destination mail server slow/down

Solution: Contact recipient, try alternative communication

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Troubleshooting Steps

Force Account Sync

1. Click Send/Receive → Update Folder

2. Or press F9

Repair Outlook Account

1. File → Account Settings → Account Settings

2. Select your email account

3. Click Repair

4. Follow the wizard

Clear Outlook Cache

1. Close Outlook completely

2. Press Win + R, type %localappdata%\Microsoft\Outlook\RoamCache

3. Delete files in this folder

4. Reopen Outlook

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Check Email Queue (For IT/Admins)

If you're an administrator:

1. Go to Microsoft 365 Admin Center

2. Navigate to Exchange Admin Center

3. Check Mail flow → Message trace

4. Look for queued or delayed messages

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Prevent Future Delays

✓ Don't send during peak Microsoft outage times

✓ Keep attachments under 25MB

✓ Maintain steady internet connection

✓ Update Outlook regularly

✓ Use Outlook on the web as backup

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Still Experiencing Delays?

Contact IT support with:

• When the issue started
• Whether it's happening to all emails or specific recipients
• Any error messages
• Your Outlook version

Still Having Issues?