Turn Outlook Suggested Contacts on or off

Suggested Contacts is turned on by default and may annoy some users, as it will automatically suggest contacts and email addresses when sending new emails.

More information: https://support.office.com/en-us/article/Automatically-add-contacts-for-everyone-that-you-send-an-email-message-5B94DB41-0029-4AA9-B326-B2FC8A2C9D7E

Turn Suggested Contacts off:

1. Click the File tab
2. Click Options.
3. Click Contacts.
4. Under Suggested contacts, select or clear the Automatically create Outlook contacts for recipients that do not belong to an Outlook Address Book.

Delete the contents of the Suggested Contacts folder:

1. In Contacts, in the Navigation Pane, click Suggested Contacts.

2. Click any contact, and then press CTRL+A.

3. On the Home tab, in the Delete group, click Delete.