The TB Address Book has fields for Email and Additional Email. The CardBook add-on has options for more addresses. Both the Email and Additional Email will appear in address autocomplete when you address a new message, but there is no option to automatically add both addresses, which makes sense.

You could create a mailing list with joe and jane as contacts, so that sending to the list sends to both contacts. Or, make a list with all of joe's addresses to send to all of them.

Edits to a contact in an address book are automatically applied to the list contact.

It did not work that way in the past. I will try it. How can I import my address book from Eudora?

Try exporting the address book as a csv and importing to TB. It might help to first edit the csv in a spreadsheet to make it easier to import.

http://kb.mozillazine.org/Importing_from_Eudora_(Thunderbird)#Address_books

http://kb.mozillazine.org/Import_address_list_from_text_file

I got the file imported. I had to edit out all the junk in excel first.

But I do not see where TB address book supports nesting. Let me try to explain how it worked in eudora joe has email joe@mail.com and joe1@mail.com under the nickname joe jane has email jane@mail.com and jane1@mail.com under the nickname jane

I make a mail list J&J that contains 'joe' and 'jane'. The list knows to go to joe and jane file to get emails. I can change joe or jane email without having to update the J&J list.

I've never used Eudora, but TB works as described above. There is no 'nesting' of email addresses; contacts can have one or more addresses that are treated independently. Mailing lists are contained in the address book that has all the list contacts; when a contact is added to a list (by drag and drop) only the Email address field is added to the list.

I was hoping for an addon recommendation that would work for me.

I think I have found a solution to my mail list issue. The 'categories' addon seems to do what I need except I have one PC on beta channel and it won't work on that. Trying to figure out how to convert it to normal channel without losing all the data..