I followed this to copy & paste the Profile folder: https://support.mozilla.org/en-US/kb/profiles-tb#w_restoring-to-a-different-location

However, this page seems to require that I do a lot of manual moving of certain files, and this page seems old; is it out of date?

http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Thunderbird

OK, most of my Addresses are not in the TBird Personal Address Book. They are in "Eudora Nicknames" from when I migrated from Eudora. Why didn't the Profile copying work on other address book folders? Sounds like a Bug to me.

OK I've manually created two of my email accounts, but how do I link the existing MAIL to them? The MAIL has been copied into the new computer's Profile.

OK, I got the Eudora Addressbook imported.

The MAIL for my main email account is showing up, but not for my secondary email account. What gives?

No, spoke too soon. All I have for both email accounts is the "INBOX" mail. There are many, MANY other mail folders. They do appear in /profile/Mail/ so how do I "activate" or "import" them so they show up functionally?

Actually all those other MAIL folders should be within Local Folders.

Within /profiles/Mail there exist several variants: "Local Folders" contains my mail "Local Folders-1" which seems to be empty.

There are 5 variants of the "pop.IPname.net" "pop.IPname-1.net" thru 4 and one without the -numeral.

The one without a numeral, and the -2, seem to be the two containing my Mail for the two different email accounts.

Maybe I should Delete the empty ones ???

There seem to be more 4 mail folders with mail in them. Only should be 3.

Also, my Message Filters did not copy into the new computer. Are they not a file in the Profile folder?

Seems like maybe the copy process did not over-write the existing items correctly ???

OK I trashed the contents of the Profile folder and copied the old. Now the Mail structure better but still missing some folders.

In the primary email, The DRAFTS folder, with 4 msgs, is missing. The SENT folder, with over 5000 messages, is missing. Also ARCHIVES with about 1400 emails.

I see that the original computers' profile/Mail/primary.email folder is missing those 3 folders, even though the appear functionally. SO where is Tbird HIDING those 3 folders, and why?????

Another problem: The colored "tags" for the primary email account have gone away. The secondary account does have at least the red tags.

Problem solved. Original poster moved his data to a location with an absolute path name and then wanted the forum to guess that.

See https://support.mozilla.org/en-US/questions/1128126

Do you remember all the preferences you set YEARS ago? The web pages on the Profile and "how to copy" it should mention that portions of the dataset might have been moved by the user.

Setting up the app to insert a file into the profile folder, saying where it has been moved (without permissions to actually access) would be good too.

VerizonSucks said

Do you remember all the preferences you set YEARS ago? The web pages on the Profile and "how to copy" it should mention that portions of the dataset might have been moved by the user. Setting up the app to insert a file into the profile folder, saying where it has been moved (without permissions to actually access) would be good too.

I am just going to file a bug to remove the option. It is not worth the support headaches it creates.