An exact estimate on how long email migration take is difficult because of the many variables involved. ShuttleCloud uses the fastest servers available, however, and we are only limited by the bandwidth that your email server allows.
A migration of a few thousand emails is typically complete in a few hours or less. Under ideal conditions we transfer anywhere from 250-750 MB per hour. A migration of tens of thousands of messages my take less than a day and a migration of hundreds of thousands of messages usually requires a day or two to complete.