I am using the beta and the Outlook import is alive and well. Thunderbird requires that Outlook app be installed on the same computer.

Thanks David. I have Thunderbird on my Apple iMac and there are only 4 options to import other emails. Outlook option is no longer there. I guess I'm going to try the ZIP option with Outlook OLM file and see what happens.

OLM has no direct conversion ability to Thunderbird. I am only aware of proprietary products. A web search for 'thunderbird olm' will show several such products. If there is a free way, I am not aware of it.