Apple Mail for El Capitan includes a feature which attempts to automatically detect the server and login settings for any e-mail account which has been created. However, this can sometimes prevent you from being able to send or receive e-mail. If you have recently upgraded to or have created an account in version 8 or higher, then it is recommended that you disable this feature.
The following steps will assist you in disabling this feature:
1. Open Mail.
2. Select Mail from the menu and click on Preferences.
3. Click on the Accounts icon and select your e-mail account from the list on the left-hand side.
4. Select the Advanced button, located beneath the row of icons at the top of the window.
5. Remove the tick from the tick box labelled Automatically detect and maintain account settings.
6. You will also need to ensure that the following settings are correct:
- Port: 110 (for POP) / 143 (for IMAP)
- Use SSL: this must be disabled
- Authentication: Password
- Allow insecure authentication: this must be enabled.
7. Once these settings have been adjusted, click on the General icon. You will be prompted to save your changes.
8. When the changes have been saved, select the Accounts icon again, followed by your e-mail address.
9. Locate the drop-down field labelled Outgoing Mail Server (SMTP); click on the field and select Edit SMTP Server List:
- In the next window, highlight the server used by your e-mail address and click on the Advanced button.
- Remove the tick from the tick box labelled Automatically detect and maintain account settings.
10. You will also need to ensure that the following settings are correct:
- Port: 587
- Use SSL: this must be disabled
- Authentication: Password
- Allow insecure authentication: this must be enabled.
Click OK to save the changes.
11. Close the Accounts window.
