This is what i did an it worked for me....(i´m using 2.9.1)
* have your database in regular exel format, make sure in the first line on each square (cell) is the title of the field ( email, name, city...and so on..)
* order in the name colums is not important..
* do not
save it as cvs format, save it as Text tab delimited
* in your control panel go to manage users > import email
* use the first option the give you: import emails with different values for attributes
* select the text file to import, you can check the Test output box to see the results before you import the file.
* do not check this boxes it´s not necesary
Field Delimiter: (default is TAB)
Record Delimiter: (default is line break)
* you can check either one of this boxes, acording to your needs
Send Notification email
Make confirmed immediately
* hit the import buttom and
* if you are satisfied with the output , go on and hit confirm Import to upload the file
* make sure the name fields on your text file (first line) correspond to the names found on the attributes page,if not no problem, if the system can´t match the fields automatically it will give you the chance to do it manually.
It should work with this procedure
Make sure your text files are small no more than 500 mails in one file.(pain in the kneck) depending on your server capability..
or you might have this error that can freeze you list system
Database error 1226 User 'website_user' has exceeded the 'max_questions' resource (current value: 50000)
if you run into this problem, don´t worry i have the pill for that too.
I hope it helps