To access the source server, you must have a user ID and password. The type of user ID and password that you require depends on the type and configuration of the source sever. Some servers support the use of an administrator account for access; other servers only support access by using individual user IDs and passwords. Prior to migration, determine which type of access the source server supports.
Servers that Do Not Support an Administrator Account
If the source server does not support the use of an administrator account, you must collect a list of mailbox IDs and passwords that are associated with the source accounts and pass the individual passwords for each account when you perform the migration. You will also have to add these mailbox IDs and passwords to the comma-separated values (CSV) file that you use to import mailboxes.
Servers that Support an Administrator Account
If you are migrating Internet mail from a server that allows you to use an administrator account for access, you can use the administrator account to access the mailboxes that you are migrating. In this case, you will only have to list the mailbox IDs that are associated with the source accounts in the CSV file that you use to import mailboxes. This enables you to bulk migrate multiple mailboxes without having to collect and pass individual passwords for each account.