If you see messages piling up in your Outlook outbox or people you're sending messages to aren't receiving them, try the following methods to fix the issue.

We've presented the methods in order of quickest to most in-depth

We recommend trying the following solutions in the order listed. Select a heading below to expand it and see details about specific steps to take:

1. Open a browser, such as Microsoft Edge or Google Chrome.
2. Try entering one of the following websites in the address bar:
1. http://www.microsoft.com
2. http://www.bing.com
3. If you can't reach either of those two websites, see Fix network connection issues in Windows.

If that doesn't fix the problem, see the next section.

If you are having sync issues, you can force a manual sync by selecting the Sync button via the View tab on the Ribbon. A status message appears at the bottom of the message list while Outlook is syncing.

Note: Third party email accounts such as Gmail, Yahoo, iCloud, or Generic POP and IMAP, do not have the same capability to manually Sync using the button.

If that doesn't fix the problem, see the next section.

Some email providers (such as your ISP or even Gmail) won't let you send messages larger than a certain size. Adding pictures and large attachments to your message can prevent you from sending that message (and any messages sent after the large message).

Go to your Outbox and then open the stuck email messages. Start with the oldest message first. If that message has an attachment that's larger than 20MB, delete the attachment and either attach a smaller file or attach a link to the attachment.

Now try to send the message again. If that doesn't fix the problem, see the next section.

If you've changed your password on the website for your email account, you'll need to change it in new Outlook, too.  

1. Select the icon next to the email account name.
2. A pop up will appear prompting you to sign in. Select Continue.
3. Follow the prompts and enter the new password to sign in.

If you know you’re using the correct password for your email account, and you see a message such as: Please create an app password for Outlook on your email provider's site.  

1. Go to your email provider to get the app password. Your email provider will provide instructions for how to generate an app password to use in email applications such as Outlook in place of your regular password.
2. After you get the app password from your provider, copy it, and then paste it when prompted for your account password in Outlook.