Data migration
There is a difference between data migration and data integration activities. Data migration is a project by means of which data will be moved or copied from one environment to another, and removed or decommissioned in the source. During the migration (which can take place over months or even years), data can flow in multiple directions, and there may be multiple migrations taking place simultaneously. The ETL (extract, transform, load) actions will be necessary, although the means of achieving these may not be those traditionally associated with the ETL acronym.
Email migration
Email Migration is a process in which an email or multiple email messages are migrated from one email client to another email client. An equivalent term is Mailbox Migration, in which case records such as e-mails, appointments, contacts or tasks may also be migrated. In general, email migration is required when a user is switching from its current email client to a new one. Usually email clients don't support similar file formats for saving mailbox data.