Export as Unix Mailbox doesn't do anything

Hello.

I am trying to get a bunch of emails out as a UNIX mailbox. When I choose the folder holding all the emails and choose Export As UNIX Mailbox, nothing happens. When I select all the emails in that folder and choose the same option, it creates something with a .mbox extension but the app that needs the correct format doesn’t recognize that.

Please help.

Thanks.

What app?

UNIX mailbox export works OK over here. Yes, in the mailbox export you need to select email documents to export – selecting a group will not export the contents of that group.

The app is Mail Archiver X. All it does is handle email.

I worked around it by importing back into Apple Mail then exporting out again, and Mail Archiver X was fine with that.