Please call support. We have a tool which will export everything if you can provide a file with a list of email addresses to be exported. This is a newer tool, so if the first tech that you talk to doesn't know about it, please ask to have the case escalated to Roxana Tehrani (Lead Support Engineer), Brandon Bishop (Escalations Engineer), or, failing that, me, the Product Manager. We'll get you taken care of.
Barracuda Message Archiver