How To Mass Delete Contacts Within the People Tab

I did try using that, the issue is the .csv file needs to be in a specific format, correct? The only .csv file I can obtain is the export from the previous data point or via Outlook.

Since it's 35,000+ total contacts, I can't format the .csv if it needs a specific format. Think maybe I can script something to export every "******@email.com" & "+1 (333) 333/3333)" & have that information exported into a .csv that could then be used w/ the proper Exchange cmdlet.

Hi @Nate 

Thank you for your response. 

The Remove-MailContact command is designed for mail-enabled contacts that reside in Exchange Online’s directory, such as those found in the Global Address List. It does not affect personal contacts stored inside a user's mailbox, which are the ones visible in Outlook or OWA. Even with a correctly formatted CSV file, this command will not remove mailbox-level contacts. 

Since Outlook and OWA can’t handle that volume, the most reliable options are: 

1.Microsoft Graph API   

First, register an app in Entra ID with Contacts.ReadWrite (delegated) or Contacts.ReadWrite.All (application).

Then, use the following API calls: 

-List all contact:

GET https://graph.microsoft.com/v1.0/users/{user-id}/contacts?$top=1000
Authorization: Bearer <access_token> 

-Filter contact with email addresses: 

GET https://graph.microsoft.com/v1.0/users/{user-id}/contacts?$filter=emailAddresses/any(a:a/address ne null) 

Or filter contact with a phone number:

GET https://graph.microsoft.com/v1.0/users/{user-id}/contacts?$filter=mobilePhone ne null 

-Delete contact (soft delete):

DELETE https://graph.microsoft.com/v1.0/users/{user-id}/contacts/{contact-id} 

-If you want to permanently delete a contact: 

POST /users/{id}/contacts/{contactId}/permanentDelete 

Note: permanentDelete is a POST action, not an endpoint under/contacts directly. 

-References:  

• Delete contact - Microsoft Graph v1.0 | Microsoft Learn.
• contact: permanentDelete - Microsoft Graph v1.0 | Microsoft Learn.

-For large datasets: 

• Use $skiptoken pagination to iterate through all pages of contacts.  
• Use /$batch to send up to 20 delete operations per request. 
• Include a short delay between deletions to prevent throttling: 

Start-Sleep -Milliseconds 200 

2.You may also consider using MFCMAPI as a manual cleanup method.  
However, MFCMAPI operates at a low level and bypasses normal safety checks, it should be used only if you have Full Access and understand the risk. If you use it, it must be done carefully and only after confirming you have full mailbox backups or retention policies enabled. 
Note: Microsoft is providing this information as a convenience to you. These sites are not controlled by Microsoft, and Microsoft cannot make any representations regarding the quality, safety, or suitability of any software or information found there. Please ensure that you fully understand the risks before using any suggestions from the above link. 

Open MFCMAPI as the user or with full access rights 

-Session > Logon > Select Outlook profile 

-Expand Root Container > Top of Information Store > Contacts 

-Right-click Contacts > Empty Folder > choose Hard Delete 

This action removes all contacts immediately from the mailbox. If retention policies or legal holds are in place, the deleted items will move to the Recoverable Items > Purges folder. 
I hope this information helps clarify the available approaches.

Hi @Nate
I wanted to follow up and ensure the information provided was useful to you. If you have any new updates or further inquiries, please let me know. Thank you!