This isn’t my specialty but I helped someone locate these registry keys which may help others so I’m posting them here.
The error symptoms are:
Summary: 1 item(s). 1 succeeded, 0 failed.
Elapsed time: 00:03:52
Failed to retrieve the properties of a message in folder INBOX for the following reason: Failed to retrieve the properties of a message in folder INBOX for the following reason: Command line too large..
The two registry keys which could help with this scenario are: The first key fixed the command too large issue, the second could help migration machines that have a limited amount of memory.
Sets the chunk size for mail extraction using IMAP. If not specified, or if the specified value is invalid then it is default to 2500.
Scenario: customer is receiving errors from the source server indicating “Request too large”. This registry key allows the customer to define a smaller request size.
Registry key to specify the pipeline memory after it grows to a certain size. Default size is 600MB, can be overridden with a registry value. This will prevent any potential System.OutOfMemroyException caused by oversized mail migration.
Scenario: Customer is receiving system out of memory exceptions on the machine running the Migration tools. The Transporter will spool up items from the source until the memory usage reaches a certain size, at which point it will flush the pipeline by submitting the items to the target server. This registry key reduces the amount of data we’ll spool up before flushing the pipeline. The other tool available for this scenario is reducing the max thread count for the migration process via PowerShell. This scenario is typically one we see on 32 bit machines.
What are the value types (String, DWORD, etc.) of ImapFetchBatchSize and PipelineFlushThresholdMB? I don't have these specified in the registry of the computer I installed the Transporter Suite on.