I have Thunderbird 91 installed and working on a MacBook Pro. Currently running OS Mojave, but will be updating that shortly to accommodate other software needs. That update will obsolete my Outlook app (Outlook for Mac 2011, v14.7.7) I have an unfortunate number of saved emails that I need to migrate to TB for future access. I have exported those to an .olm file, but TB doesn't recognize it, and neither does Apple Mail as an intermediate step to a mailbox file (sorry, I don't know the suffix). Guidance appreciated, otherwise I just have to s**k it up and spring for a new version of MS 365 to get a new version of Outlook.