Hello,
this is a setting in Outlook.
Turn Suggested Contacts on or off
Suggested Contacts is turned on by default. Because Suggested Contacts is considered part of Outlook Address Book, some synchronization programs might attempt to synchronize the contacts to other devices.
The Suggested Contacts folder can contain a large number of entries. To prevent synchronization of the Suggested Contacts folder, review the documentation provided by your synchronization software. You can also exclude the folder as part of the Outlook Address Book. This might prevent the folder from being synchronized with other devices.
1.In Contacts, in the Navigation Pane, click Suggested Contacts.
2.On the Folder tab, in the Properties group, click Folder Properties.
3.On the Outlook Address Book tab, clear the Show this folder as an e-mail Address Book check box.
If you want to turn Suggested Contacts off, do the following:
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.
You might also want to 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.