Thunderbird 56 hasn't been released yet. Thank you for testing a beta version. You can't expect all addons to magically work with beta versions.

I doubt there is any change in the folder structure of that version. Whatever information you have found about the profile for previous versions will still apply.

https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data

But ImportExportTools remains your best bet for selectively importing from an older profile.

I fully understand the risks of running beta versions. I used to play with nightlies. From their website I did find a version of ImportExportTools that will install on 56.0b4. I asked because the storage setup in TB 56 seems to have changed.

What changes have you noticed?

> I asked because the storage setup in TB 56 seems to have changed. Nothing has changed afaik.

Why do you need to export anything? Do you have pop accounts or much mail in local folders?

And if it won't run, then a) there is probably something in tools > error console b) you should probably contact the author of the addon

I have solved the problem. First, I had a great deal of downloaded email from my LDAP servers. I prefer local storage in a strongly encrypted environment. I also had a large collection of filters. My solution was to create a new profile and redefine my LDAP connections. I then copied all of the Mail folder from the old profile to the new one. All my local email storage reappeared. I then copied each of the msgFilterRules.dat files from the LDAP folders in the old profile to the same place in the new profile. My filters also work fine.