Mail migration fails with the following error message:
CONFIG_TEXT: Failed to copy mail content of subscription. Most probably that happens because of a network-related issue. Check network connections between source and target servers, then run migration for that subscription once more.
Migration tools tried to perform operation in 3 attempts: Command execution failed on the local server with non-zero exit code.
command: "C:\Program Files (x86)\Plesk\admin\plib\modules\panel-migrator\backend\lib\python\parallels\core\extras\mail-migrator\windows\MailMigrator.exe" list-message-ids --account-description-file="C:\Program Files (x86)\Plesk\var\modules\panel-migrator\sessions\20191015091512\target-server\mail\example.com\jonn.doe\mailbox-description" --output-file="C:\Program Files (x86)\Plesk\var\modules\panel-migrator\sessions\20191015091512\target-server\mail\example.com\jonn.doe\exclude-message-ids"
exit code: 2
stderr: Error: Object reference not set to an instance of an object.
SmarterMail 16.3 or higher (17.x, SmarterMail 100) is installed on the destination server.
Migration to and from SmarterMail version 16.3 or higher is not yet supported. It is a known Plesk Migrator bug with the ID PMT-4672 and will be fixed in the next Plesk Migrator update.
Currently, no workaround is available.