Unable to suppress system-level work item notifications during cross-organisation migration

[SiddeshwarMerkle]

We are performing a cross-organisation Azure DevOps migration from legacy.visualstudio.com to dev.azure.com/projects using the Azure DevOps Migration Tools (devopsmigration v16.3.4-Preview.10).

During work item migration, the tool replays all historical revisions of each work item. This triggers email notifications to users who were mentioned, assigned or involved in those work items.

What we have tried:

Disabled all org-level notification subscriptions in target org
Disabled all project-level notification subscriptions
Users disabled personal notification subscriptions
Both orgs are on the same Entra ID tenant - ADO resolves user identities even if they are not members of the target org

Issue:
Despite all notification settings being disabled, users are still receiving emails with the message “We sent you this notification because you were mentioned.” This appears to be a system-level notification sent directly by Azure DevOps that bypasses all configurable notification settings.

Expected behaviour:
Disabling org-level or personal notification subscriptions should suppress all notifications including mention notifications.

Actual behaviour:
Mention notifications are sent regardless of notification settings — no admin-level control exists to suppress them.

Question:
We want to migrate all work items from Azure Boards without these notifications being triggered. Is there any way to suppress mention notifications at tenant or platform level during a migration window? Or is this a known limitation?

Microsoft suggested using the suppressNotifications flag on the REST API during migration to stop notifications from being sent on create and updates:

https://learn.microsoft.com/en-us/rest/api/azure/devops/wit/work-items/create?view=azure-devops-rest-7.2

However, it is unclear whether the Azure DevOps Migration Tool supports this flag. Could you confirm if suppressNotifications=true can be passed through the tool's API calls, or if there is a config option to enable this?