There are no particular restrictions for migration. However, experience has shown that not all formats are appropriate to every situation. There are many aspects of a migration to consider that can influence whether to use an offline or online model, whether to leverage Sun partners, and so on. Consider the following factors when determining your migration:
Number of users. Small companies with fewer than 100 users and simple requirements might want to use an offline migration model.
Existing Service Level Agreements. Companies that have mission critical SLAs can only use an online migration model, ensuring no end-user service interruption.
Developing New Service Level Agreements. Companies might want to take the opportunity to revisit their mission-critical service under an SLA. You might even want to outsource support to a business-to-business messaging hosting platform from the Sun customer network.
Identity Management. Companies that have or want a more mature provisioning model can use this opportunity to revisit their identity workflow. Consider starting a Sun Java System Identity Manager project prior to the migration project. For more information, see: http://www.sun.com/software/products/communications/partner_library/index.xml
Third-party Applications. Companies that use third-party or in-house applications on Microsoft Exchange should consider rehosting these applications with Sun Java System Portal Server and Sun Java Integration Suite offerings. You need to review specific applications, such as voice-based systems, unified messaging, integration with fax, and so forth, on a case-by-case basis.
Distributed Topology. Companies with most or all system components and messaging processes distributed across multiple sites will want to consolidate. This process requires pre-project work. In particular, data centers need to consider networking, security, and even disaster recovery.
Unsolicited Bulk Email (UBE). You might want to take this opportunity to include revisiting your anti-virus and anti-spam plan. Sun Java System Messaging Server offers many anti-virus and anti-spam tools, including mailbox filtering, address verification, relay blocking, and integration with various third-party anti-virus and anti-spam products.
Archiving. As part of a migration, companies might want to add some archival features (in addition to your backup plan) to their messaging system. You might also want to introduce compliance and content management systems. Sun currently partners with AXS-One on compliance systems. For more information, see: http://solutions.sun.com/partner/pd/PartnerDetail.jsp?vendor_id=1019722
Choosing a new desktop. Companies concerned with support costs, TCO, and so forth, might want to take this opportunity to consider removing the Microsoft Windows desktop itself, and use an alternative such as Sun Java Desktop System.
There is no single answer to cover all of these situations. As such, Sun and its partners take the time upfront during a two-day workshop to assess the particulars of your organization to arrive at the correct way to handle your migration. See Workshop Phase (Validate Architecture and Methods) for more information.