To produce a CSV report of mailbox status per collection take the steps below:
1) Open SQL management studio
2) Right click the relevant project name (MMEXProject in the screenshot example) and choose New Query
3) User the query below:
DECLARE @ID INT
SET @ID=(SELECT TOP 1 [ID] FROM COLLECTION WHERE Name = 'the name of your collection')
exec GET_COLLECTION_STATS @ID
*NOTE - the collection name is case sensitive
4) Right click anywhere on the data and choose "Save Results As..."
Interpreting the Mailbox Status Codes:
Unknown = 0
New = 21
InProgress = 22
ReadyToSwitch = 23
SwitchedCompleted = 24
Failed = 25
NativeMoveCompleted = 27
Deleting = 28
Provisioning = 29
Switching = 31
Unswitching = 32
MovingInTarget = 33
SwitchedFinalSync = 34