Aspects of the subject matter described herein relate migrating message for a messaging service. In aspects, a determination is made that messages need to be migrated based on a threshold being crossed. In response, an agent is instructed to migrate data associated with the messages to another location. The agent uses various factors to determine one or more queues to migrate. While a queue is being migrated, during a first portion of the migration, messages may be added to and removed from the queue as senders send new messages and receivers consume messages. During a second portion of the migration, the queue is frozen to disallow the queue to be used for receiving new messages and delivering queued messages. The migration may be orchestrated to attempt to achieve certain goals.