Uncheck the option labeled Automatically detect and maintain settings.

Under Outgoing Mail Server (SMTP), select Edit SMTP Server List.Now click on the Account Information tab.Uncheck the option labeled ' Automatically detect and maintain settings.This only applies to Apple computers running Yosemite. We suggest following these steps to ensure your account settings don't change if you're running Yosemite. Check the box to Always trust the certificate.If you receive this message, follow these steps: If you choose to use SSL, you may receive a message warning that the certificate is not trusted. Click on the Outgoing Mail Server drop down menu and select Edit SMTP. Please see the SSL Certificate Warning for the next steps. Click on the Mac Mail account you wish to edit It should be your RCN account. Click on the '' or ': If you choose to use an SSL, you may see an SSL warning.Tap the email account from which you want to send emails (or add a new one if it’s the case). Click on the 'Outgoing Mail Server (SMTP)' selection menu and click 'Edit SMTP Server List' Select Settings > Mail, Contacts, Calendars.'Outgoing Mail Server (SMTP)' should be '' if your e-mail address ends in '', otherwise it should be ''.'User Name' should contain your full e-mail address.'Incoming Mail Server' should be '' if your e-mail address ends in '', or '' if your e-mail address ends in ''.In the right pane, verify the following settings:.In the left hand column, verify that your Physics or Astronomy e-mail account is selected.From the 'Mail' menu, select 'Preferences'.The process for doing so is outlined in the video screencast and step-by-step instructions provided below. Uncheck Automatically manage connection settings if you want to. Next, click the + under the list of SMTP servers, and add a new one. In the event that Apple Mail is no longer able to access your e-mail, it may be necessary to review and update some of the account settings. SMTP Settings Click on the Mail option in the top toolbar A dropdown menu will appear Click on the Preferences option The preferences pop up window will. On the account you want to edit, click the tab that says Server Settings, then click the Outgoing Mail Account dropdown and select Edit SMTP Server List.

Apple mail smtp settings