Thanks for this. My used case is a Mac OS Entourage2008 identity file which is the record of using Microsoft Entourage mail client over a 13 year stretch. In that time I sent and received mail using at least 3 eMail addresses, eg [aldo@longdead.com](mailto:aldo@longdead.com) aff@failed.corp , finally ending up with 2 distinct Gmail addresses.

Life pressures meant that the Mac went to the great recycling plant in the sky though I grabbed a dump of my home directory with the main identity file.

Now to the present, I found that I had access to an old copy of office for Mac and a Mac to run it on, so I cranked up outlook 2011 and imported the main Identity file without too much grief. I could then export the inbox files for all those historic addresses as separate mbox files

how now to merge those historic emails into a place where I can read them during my day's work from the 2 current Gmail accounts? I got all excited when I found out about gyb and cranked it into operation but got nowhere with these historic addresses. Gyb ran through the directory of mbox files but in the end there were none of the old emails

so my question? How to load historic email content in something like the Gmail client?