How can I, as an Exchange administrator, set when deleted contacts are permanently removed from the trash?

When an employee leaves the company, their contact is removed from the central source (e.g., Microsoft Entra ID / GAL). sync.blue® automatically synchronizes this change to all connected Exchange mailboxes. Depending on the deletion strategy, the same deleted contact may appear simultaneously in the “Deleted Items” folder in many mailboxes.

Why do deleted contacts appear in the trash?

This is the standard behavior of Microsoft Exchange Online:

1. sync.blue® notifies Exchange that a contact no longer exists in the source.
2. Exchange deletes the contact in the user's mailbox.
3. Deleted contacts are automatically placed in the “Deleted Items” folder.
4. Afterwards, they move to “Recoverable Items > Deletions”.
5. The retention period is 14 days by default, with a maximum of 30 days.

This means: Without further action, an employee’s departure remains visible to staff for several days.

The solution: Significantly reduce the retention period for deleted items

To prevent a deleted employee contact from being visible in many users’ trash folders for days, the “RetainDeletedItemsFor” setting for all Exchange mailboxes should be shortened — ideally to 1 to 3 days.

This ensures that deleted contacts disappear extremely quickly and that no personal departure information is visible.

How to centrally set the retention period via PowerShell

For all Exchange user mailboxes

Get-Mailbox -ResultSize unlimited -Filter "RecipientTypeDetails -eq 'UserMailbox'" |
Set-Mailbox -RetainDeletedItemsFor 3

This will retain deleted contacts in the trash for a maximum of 3 days. (the maximum allowed is 30 days)