Mailmate crashes when message moved between account

I moved a message with this keybinding:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<array>
    <string>moveToMailbox:</string>
    <string>imap://ingo%40mm.st@mail.messagingengine.com/BH TODOs</string>
</array>
</plist>

This does work, if used against a message in the same mailbox (same account, just move to an other folder) but fails if moved from one account to an other.