How to Make macOS Mail Keep a Copy of Messages on the Server

One feature of POP email accounts is that you get to choose how your emails behave once they've been downloaded to an email client. macOS Mail lets you make this change so that you get to decide whether to have your emails deleted or kept on the email server.

If you do keep mail on the server, you can grab a second copy from this online "backup" if you inadvertently delete an important email. You can also download the same messages to another email program on another device.

However, if you have all mail removed from the server immediately after downloading it in macOS Mail, while you don't risk having your mailbox filled with hoards of old mail, you do miss out on the opportunity to download those messages on other devices.

Fortunately, you can get the best of both worlds by keeping a copy of emails on the email server for a particular amount of time.

1. Navigate to the Mail menu and choose Preferences... from the drop down selection.
2. Make sure you're in the Accounts tab at the top.
3. Choose the POP email account you want to edit from the left pane.
4. From the Account Information tab, make sure there's a check in the box next to Remove copy from server after retrieving a message.
   1. Note: In older versions of the Mail app, you might need to first go into the Advanced tab.
5. From the drop down menu just below that check box, choose After one day,  After one week, or After one month.
   1. For example, if you pick the first option to delete the emails after one week, then once the messages are downloaded to macOS Mail, they will be automatically removed from the email server one week later. This means that you can download the same messages on other computers and devices within that week only.
   2. Note: There's also a When moved from Inbox option that you can pick instead which will, of course, delete emails from the server only after you move the messages away from the Inbox folder.