The Unwanted Recipients
The Apple Mail application on macOS is designed to speed up your workflow by remembering every single person you have ever emailed. When you start typing a name in the “To:” field of a new message, Mail automatically suggests a list of contacts. However, this list includes not just people in your address book, but “Previous Recipients”—people you emailed once five years ago, mistyped addresses, or old corporate emails that no longer exist. This automatic suggestion can easily lead to accidentally sending a sensitive email to the wrong person simply because they had a similar first name to your intended recipient.
Clearing the Previous Recipients List
To ensure you only email verified contacts and stop macOS Mail from automatically suggesting outdated or incorrect addresses, you must manage and clear the hidden “Previous Recipients” database.
Open the Mail application on your Mac. Navigate to the top menu bar, click on Window, and from the drop-down menu, select Previous Recipients. A new window will appear showing a massive list of every email address the app has remembered. You will notice that addresses actually saved in your Contacts app have a small card icon next to them; the rest are just cached history. You can click to select individual addresses you want to forget, or press Command + A to select the entire list. Once selected, click the Remove From List button at the bottom left of the window. Mail will immediately stop suggesting those deleted addresses when you compose new messages.