Apple's built-in mail application (appropriately named Mail) is a fantastic email client for many reasons. The biggest advantage is the searchability that it offers. In addition to incredible searching, Mail also has some really nice tools built-in for troubleshooting account access issues (incorrect password, error in the settings, etc).
If you can’t send or receive email on your Mac, you can use Mail Connection Doctor to learn more about the issue. Mail Connection Doctor checks the status of your Internet connection and each of your email accounts.
Open the Mail app, then go to Window > Connection Doctor.
Check Internet connection status
The top of the Mail Connection Doctor window shows the status of your Internet connection. If you see a red dot, Mail can't connect to the Internet. If Mail can’t connect to the Internet, it also can't use any of your email accounts to send or receive email. Click the Network Diagnostics button to start a detailed test of your Internet connection, then learn about solutions for connecting to the Internet.
Check email account status
If you're connected to the Internet but Mail Connection Doctor shows a red dot next to one or more of your accounts, check the Details column for messages such as the following:
“Trying to log in to this . . . account failed.”
Your email service may be experiencing a service outage. Contact them or use their status webpage to make sure that their mail service is online. You may also get this message if the password for your account is missing or no longer valid.
“Could not connect to this . . . server.”
The settings for your email account may not be correct. Check Mail preferences to make sure that your email account settings are up to date. You can use the Mail Settings Lookup tool to check the settings for many email providers, or get them from your email provider.
You may also see this message if a network firewall is blocking the connection to your email service. That can happen if you installed third-party firewall software, or you're on a different network that doesn't allow the necessary email connections. If you're connecting from your corporate network, contact your corporate IT department for help. If you're connecting from somewhere else, such as a coffee shop or Internet cafe, check with their staff.
Show more detail
Mail Connection Doctor can show even more detail about the connection:
- Click the Show Detail button to open a drawer showing basic communication between the Mail app and your email service. If the drawer is empty, click Check Again to start another check. You can copy data from this drawer and paste it into another app for easier viewing. Messages that contain "ALERT" come directly from your email provider.
- Select the Log Connection Activity checkbox to cause Mail to generate detailed logs of its communication with your email service. To view the logs, click Show Logs. To stop logging, deselect Log Connection Activity.