Can’t connect? Always check the Service Health Dashboard first – if there is a service issue in progress, the solution may be out of your hands. If there isn’t a service issue, you can use these troubleshooting tips to help find the source of the problem.

Common causes of email connection problems

  • DNS records for your organization aren’t set up. An MX record is required to receive email. A CNAME Autodiscover record is required to allow connections through Outlook. An SPF record lets other organizations know your email came from a trusted source.
  • DNS records for your organization need to be changed. If your organization was recently migrated or received a service update, you may need to update your DNS records.
  • Outlook profiles are set up to use a specific server name instead of using Autodiscover. We need to be able to move mailboxes around for datacenter maintenance and service updates, so use of Autodiscover is required by your organization to make sure we don’t break things for you.
  • Unsupported version of Outlook. The version of Outlook that you are using has to meet Office 365 requirements and should also have all of the latest updates applied. We recommend using Windows Update so that your version of Outlook always has the latest software updates.

Troubleshoot and resolve issues

I can’t send email

Check for the existence of the SPF record. The SPF record is used to prevent phishing and spoofing. Organizations that receive email from you can check for this record to make sure that email was sent from a trusted source.

I can’t receive email

There may be a problem with your MX record. You can use an online tool to look up all the MX records associated with your domain (search for "DNS lookup tool"). You should see an MX record for each domain you use to receive email, and it should match the MX record that is displayed in the Office 365 admin center exactly. There should be no “extra” MX records, which could cause email to be delivered to the wrong place.

Go here to view the MX records for your organization. Select the custom domain, then click View DNS settings > View DNS records.

Note: if you’re having trouble receiving mail from only one domain, it’s possible that the other organization has set up a connector specifically for sending email to you, and that they’ve set that connector to go to a specific IP address. They should update the connector to use DNS resolution instead.

I just got upgraded and can't get Outlook to connect to Exchange Online

Solutions for the most common issues with Outlook are listed below. You can also use the Outlook connectivity troubleshooter to find a solution, including some that are not shown here.

Also see Fix outlook connection problems after Office 365 upgrade

Outlook connectivity issues can be frustrating, especially when you have a bunch of upset users who expect you to get it fixed now. The good news is that while you're working on the problem, users can continue to connect to Outlook Web App to send and receive email, schedule meetings, and lookup contacts.

The most common causes of this problem are a missing or misconfigured Autodiscover DNS record or an Outlook profile that is configured manually. Exchange Online supports Outlook connectivity only through Autodiscover. Just like it sounds, this DNS record lets Outlook automatically discover the location of your mailbox. If your Outlook profile is set up to use a specific server name, your connection can break if the mailbox is moved, such as during an upgrade. To see if this is your problem and get it fixed, follow these steps:

  1. Use the Microsoft Remote Connectivity Analyzer to test Autodiscover for an account in your organization. If the test fails, move on to step 2. If the test succeeds, go right to step 3.
  2. Set up (or correct) the CNAME record for Autodiscover. It's shown in the DNS settings for your domain. Then follow the steps to Set up email in Outlook 2010 or Outlook 2013.
  3. Try to repair the account. Go to Account settings in Outlook, select the Office 365 account, and then click Repair. You shouldn't have to create a new Outlook profile, except as a last resort.
  4. Check that the version of Outlook that you're using meets Office 365 requirements and also has all of the latest updates applied.

Need more detailed steps? See Correcting Autodiscover and DNS settings.

Everything was working just fine and then Outlook just quit connecting

Solutions for the most common issues with Outlook are listed below. You can also use the Outlook connectivity troubleshooter to find a solution, including some that are not shown here.

There is more than one possible cause to this symptom. The most common solutions are listed here.

  • Outlook uses a process called Autodiscover to automatically find your settings and set up an Exchange connection to your account. If the Outlook profile is set up to use a specific server name instead of using Autodiscover, the connection may break if your mailbox is moved. Make sure that you’ve set up the CNAME record for Autodiscover. It’s shown in the DNS settings for your domain. Then follow the steps to Set up email in Outlook 2010 or Outlook 2013.
  • Check that the version of Outlook that you’re using meets Office 365 requirements and also has all of the latest updates applied.
  • Try to repair the account. Go to Account settings in Outlook, select the Office 365 account, and then click Repair.
  • If you’re still having problems with Outlook, follow these troubleshooting steps.

I added a custom domain, but email sent to that address isn’t received

  1. Make sure that you have set up the MX record for the custom domain. See I can’t receive email for that step.
  2. Make sure that user accounts are licensed to use Exchange Online.
  3. Set up user accounts to use the custom domain as their email address. View the Exchange settings for the user and verify that they have an email address for the custom domain. You can add the email address if it’s not there. A user can have more than one email address, but only one can be set as the primary address. Read more about managing user mailboxes.

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