When Apple Mail encounters a problem with an e-mail account, it will often show a message stating that account is "offline". This message can be misleading as it means that Mail is unable to communicate with the e-mail server, which could be due to a number of reasons.
If you see this message in Mail, you should do the following:
1. Restart the program.
2. Check whether you have an active Internet connection. If your connection is down, then Mail will not be able to connect to the server.
3. Ensure that your server settings are correct. Should any of these settings be incorrect, then Mail will not be able to communicate with the server. This is often caused by Mail automatically adjusting your settings.
You can use the following guides to check this:
4. Do you connect to the Internet via a managed / corporate network? If so, then your network administrator will need to ensure that ports 110, 143 and 587 are open. If these ports are closed, Mail will not be able to connect to the e-mail server.
If you continue to experience difficulty, please contact our support team for assistance.