There are several potential reasons why emails are being sent to the wrong contacts or recipients in Outlook. To troubleshoot the issue, try the following steps:

1. Check the Email Address Autocomplete list. Some outdated or incorrect addresses in Autocomplete can be causing this issue.
2. Verify that you are using the most current version of Outlook.
3. Check for any corrupted contacts on your device.
4. Verify the outgoing server is correctly configured.
5. Check to see if there isn’t malware that’s causing the issue.
6. Verify that the address is typed correctly and formatted correctly.