I suggest possibly editing the first line of your CSV, assuming it has header info. Change the name of the column for primary email to be Primary Email and I think you will be successful. I duplicated the problem to test it, and 'Primary Email' is an option on the import.

Hi, David, Yes and no. It moves the solution a little closer.

I created multiple copies of my .csv one after the other, because there are multiple headers with the word :"E-mail" in them.

One of the "E-mail" columns has only the email address, another has the "display as" info.

No matter what I do - change the first line column header in turn, or delete the "display as" column, nothing gets only the email address in the outlook profile "email" In fact, when I renamed the column with only the email to Primary Email" and deleted the "display as" column, it didn't pull over any email addresses. What it will take - and only the info there - is the "display as" and put that in as the email address. That "display as" info looks like this in Thunderbird in the "email addresses" box:

office@somewhere.org %SMTP %Lizzie Borden(office@somewhere.org)

Okay, Your solution did work, I just didn't understand it at first!

Adding the "Primary Email" in the Outlook.csv first line added "Primary Email" in the Thunderbird list, as you said it would (that was the bit I didn't understand).

However, I had already played with the "Address Book Field" drop-downs for other things in that list, like Email 2 for instance, and so I had to uncheck those so that I could correct "Address Book Field" for "Primary Email" - now it's all good! thank you!

You're very welcome .