How do I map or merge the source E5.5 mailbox to the target account between Organizations, without a (NETIQKB18321)

goal
How do I map or merge the source E5.5 mailbox to the target account between Organizations, without a common SMTP address, SamAccount Name, SidHistory, or Domain Migration Administrator (DMA) mapping?

fact
Exchange Migrator 2.x

fix
Exchange Migrator (EM) alone can not merge the accounts in this scenario. A workaround is to run the Import Objects for Post Migration Tasks in Domain Migration Administrator to create the DMA mapping.  Then import the Domain Migration Administrator mappings in Exchange Migrator.

note

For more information on importing objects into DMA and EM please see the following Knowledge BAse articles.

• NETIQKB9719 - How do I import mapping information for an existing source and target account into the migrated objects table in DMA using a CSV file?
  https://www.netiq.com/kb/esupport/consumer/esupport.asp?id=NETIQKB9719 
  
  
• NETIQKB1177 - How can you import Mappings into Exchange Migrator (EM) from DMA?
  https://www.netiq.com/kb/esupport/consumer/esupport.asp?id=NETIQKB1177

Formerly known as NETIQKB18321