Why won't IE allow me to bcc a category of 17 contacts?

I am getting an error message from Internet Explorer that tells me that the names have exceeded the limit in the bcc. I emailed Yahoo for help and their answer didn't address the problem at all. From what they said, I should be able to do this but IE won't allow it. I

I simply want to keep my contacts' email addresses private while I send one message to a group of people. How can I do this? Thank you.

Why won't IE allow me to bcc a category of 17 contacts?internet browser

It's not IE.

Have you recently upgraded to the New Mail ??

If so----that's the problem.

For some unknown reason the New Mail doesn't recognize categories nor will they send them.

Switch back to Classic and your categories will be sent as usual.

Top of the mail page, next to "sign out", click the link "Mail Classic". OR use this link--and click "yes".

http://us.mg1.mail.yahoo.com/dc/optout?s...

Afterwards, (if you want) you can switch back to New Mail, by clicking that same link, which will now say "All-New Mail". OR use this link.

http://advision.webevents.yahoo.com/mail