Microsoft 365 Email Not Syncing? Easy Steps to Fix It

Email not syncing across your devices can quickly become frustrating, especially when messages appear on one device but not another. Microsoft 365 and Outlook email sync problems can be caused by internet connectivity, account settings, outdated software, authentication issues, or problems with the mail app.

The good news is that many common sync problems can be checked and resolved with a few practical troubleshooting steps.

This guide explains what to check when your Microsoft 365 or Outlook email is not syncing properly across your computer, phone, tablet, or other devices.

Why Is My Microsoft 365 Email Not Syncing?

When email stops syncing, the problem can come from several different areas. Common causes include:

• Unstable or interrupted internet connectivity
• Incorrect Outlook account settings
• Authentication or password problems
• Outdated Outlook or Microsoft 365 software
• Problems with the Outlook profile
• Mobile email app settings
• Background sync restrictions
• Server or Microsoft 365 service issues
• Problems with the way the email account has been configured

Before making major changes to your account, start with the simple checks below.

Check Your Internet Connection

Outlook needs a working internet connection to send and receive messages from the Microsoft 365 service.

If your connection is unstable, Outlook may remain open while new messages fail to arrive.

Try these steps:

1. Open a web browser and visit a few websites.
2. Check whether other devices on the same network have internet access.
3. If you’re using Wi-Fi, move closer to the router if possible.
4. Restart your router if the connection appears unstable.
5. Try connecting through another network if available.

If other websites work normally but Outlook still isn’t synchronising, continue with the next steps.

Check Whether Outlook Is Connected

Outlook can sometimes appear to be working while it is actually disconnected from the mail service.

Look at the connection status within Outlook and check for messages such as:

• Working Offline
• Disconnected
• Trying to connect
• Password required
• Need password

If Outlook is set to Work Offline, disable that option and allow it to reconnect.

You can then try sending and receiving email again.

Check Your Microsoft 365 Account Settings

Incorrect account configuration can prevent email from synchronising correctly.

Check that:

• You are signed in to the correct Microsoft 365 account.
• Your email address is correct.
• Your password is current.
• Your account has not been disconnected.
• Outlook is using the correct account profile.
• You are not being asked to complete an authentication step.

If your Microsoft 365 password was recently changed, Outlook or another email application may need you to sign in again.

Try Sending and Receiving Email Manually

If new messages are not appearing automatically, try a manual send and receive.

In Outlook, use the Send/Receive option to check for new messages.

If the manual sync works, the problem may be related to automatic synchronisation or the Outlook application’s connection rather than the mailbox itself.

If manual synchronisation also fails, continue troubleshooting the account and application.

Update Outlook and Microsoft 365

An outdated Outlook application can sometimes cause compatibility or synchronisation problems.

Check whether Microsoft 365 or Outlook has any available updates.

After installing updates:

1. Close Outlook.
2. Restart your computer.
3. Open Outlook again.
4. Allow the application time to reconnect.
5. Check whether new messages are now appearing.

Keeping Microsoft 365 applications updated can also help address known bugs and compatibility problems.

Check Outlook Sync and Account Settings

If Outlook is connected but messages are still not appearing correctly, review the account and synchronisation settings.

Check whether:

• The correct folders are being synchronised.
• The account is still active.
• Outlook is downloading new messages.
• Any offline settings are limiting synchronisation.
• The account has been configured correctly.

If the account was recently added to Outlook, removing and adding it again may sometimes resolve configuration problems.

However, don’t remove the account immediately if you have important locally stored Outlook data. Make sure important information is backed up or otherwise available before making significant account changes.

Check Your Microsoft 365 Email on the Web

One of the easiest ways to determine whether the problem is with the mailbox or with Outlook is to check your email through the web.

Sign in to your Microsoft 365 webmail account and check whether:

• New emails are appearing.
• Recently sent emails are visible.
• Your folders contain the expected messages.
• You can send a new email.
• The mailbox appears to be working normally.

If email works on the web but not in Outlook

This can indicate that the issue is specific to the Outlook application, local configuration, or the device.

If email also fails on the web

The problem may be related to the account, Microsoft 365 service, authentication, or another server-side issue.

This distinction can help narrow down the problem before making changes to Outlook.

Microsoft 365 Email Not Syncing on Your Phone?

Email can work correctly on your computer while failing to update on a phone or tablet.

If your mobile device isn’t receiving new messages, check the following.

Check your internet connection

Make sure the phone has a working Wi-Fi or mobile-data connection.

Try opening a website or another online application to confirm the connection is working.

Check battery-saving settings

Some phones restrict background activity to save battery.

If your email application is prevented from running in the background, new messages may not appear until you manually open the app.

Check the device’s battery or background-app settings.

Check app permissions

Make sure the email application has the permissions it needs to operate correctly.

Check sync settings

Open the email application’s account settings and make sure synchronisation is enabled.

Remove and re-add the account if necessary

If the account configuration appears to be corrupted, removing and adding the account again can sometimes resolve the problem.

Before doing this, make sure you know the correct account credentials and that important email is safely stored in the mailbox.

What Is the Difference Between Exchange and IMAP?

The way an email account is configured affects how messages and other mailbox information are synchronised.

Exchange

Microsoft 365 business email accounts commonly use Exchange-based connectivity.

Exchange can provide synchronisation of mailbox information across supported devices and applications, including email and other account data.

IMAP

IMAP primarily synchronises email messages and folders between the mail server and an email application.

It does not provide the same functionality as an Exchange-based Microsoft 365 account.

If a Microsoft 365 account has been configured using an inappropriate or outdated connection method, it can result in differences between devices.

For Microsoft 365 business accounts, checking that the account has been configured using the appropriate Microsoft-supported method is important.

Outlook Email Sync Errors

Specific Outlook errors can provide clues about what is preventing synchronisation.

For example, you may encounter problems related to:

• Outlook data files
• Server connectivity
• Authentication
• Account configuration
• Network connectivity
• Outlook profiles

Rather than repeatedly restarting Outlook without identifying the cause, note the exact error message or code.

A specific error message can make troubleshooting much faster because it gives you a starting point for identifying the underlying problem.

Check Whether Microsoft 365 Has a Service Issue

Sometimes the problem isn’t caused by your computer or Outlook installation.

Microsoft 365 services can experience temporary service interruptions or other issues that affect email access.

If multiple users are experiencing the same email problem at the same time, check the Microsoft 365 service status or ask your Microsoft 365 administrator to investigate.

This is particularly important for business environments where several employees suddenly stop receiving or sending email.

Restart Outlook and Your Computer

It sounds simple, but restarting can resolve temporary application or connection problems.

Try this sequence:

1. Close Outlook.
2. Save your other work.
3. Restart the computer.
4. Open Outlook.
5. Wait for it to reconnect.
6. Send yourself a test email.
7. Check whether the message arrives.

If the problem keeps returning after every restart, further investigation is needed.

Repair or Reconfigure Outlook

If basic troubleshooting doesn’t resolve the issue, the Outlook installation or profile may need further attention.

Depending on the situation, troubleshooting may include:

• Checking the Outlook profile
• Repairing Microsoft 365 applications
• Creating a new Outlook profile
• Reconfiguring the Microsoft 365 account
• Checking authentication
• Reviewing Outlook data files
• Removing a corrupted account configuration

These steps can affect locally stored Outlook information, so they should be performed carefully.

For business users, it is often better to have an IT professional check the configuration before making significant changes.

What If My Email Still Isn’t Syncing?

If you’ve tried the steps above and Microsoft 365 email still isn’t synchronising, the issue may require a more detailed investigation.

The problem could involve:

• Microsoft 365 account configuration
• Outlook profile problems
• Authentication
• Device configuration
• Network connectivity
• Microsoft 365 service availability
• Email application configuration
• Multiple-device synchronisation issues

If the issue affects a business account, continuing to make random configuration changes can sometimes make troubleshooting more difficult.

A professional IT support provider can check the account, device, Outlook configuration, and Microsoft 365 environment to identify the underlying problem.

When Should You Get Professional Microsoft 365 Support?

Consider getting professional assistance if:

• Multiple employees are affected.
• Email has stopped working across several devices.
• Outlook repeatedly disconnects.
• Users cannot send or receive messages.
• Authentication problems keep returning.
• Microsoft 365 accounts are not synchronising correctly.
• Email works on one device but not another.
• The problem returns after temporary fixes.
• You are unsure whether changing Outlook settings could affect important business data.

For businesses, resolving email problems quickly can help minimise disruption to communication and daily operations.