This is a restriction with any legitimate e-mail program and any legitimate e-mail service provider.

If you write one e-mail and put in a huge list of people to send it to, this is a "mass e-mail". Mass e-mails are discouraged because some (or many) of the people receiving such an e-mail may not want it. Like spam e-mail or "mass marketing" e-mails.

If you are involved in "mass marketing" or spamming, then do not use Thunderbird. While I can only speak for myself, I am sure that no one here wants anything to do with spammers or "mass marketers".

If you have a legitimate reason for sending the same e-mail to 90 people, then you need to make use of legitimate e-mail list services. I don't know about them, do not want to know about them, so will not suggest any.

http://kb.mozillazine.org/Limits_(Thunderbird)#E-mail_addresses

"There appears to be a limit of approximately 60 addresses when sending messages if you enter each address separately. However, if you use lists (mail distribution lists) for most of the addresses any limit is imposed by whatever SMTP server you use."

Well, my purpose is legitimate - a closed group of businessmen, of which I am a member. For what its worth, I do use "legitimate" e-mail services to manage access to much larger, groups that have voluntary, opt-in subscribership. My attempt here was simply to "reply all" to a group inquiry from the President of our group in email account I manage with T'Bird.

I would not expect anyone responding here to want anything to do with spam - nor do I... If I did, I certainly wouldn't send out a support inquiry for instructions. I simply asked a question about functionality, which in this case Thunderbird chooses not to provide. A simple answer without assumption would be sufficient .

sfhowes - Thanks!

Tdub73 said

My attempt here was simply to "reply all" to a group inquiry from the President of our group in email account I manage with T'Bird.

If you wish to create a mailing list or address book from a message that contains several CC addresses, see this post.

Thanks - can you tell me what folder / where to place the xpi file- or otherwise how to implement the address crawler?

The xpi file is the add-on installer. To install the add-on, see this page (or just drag the xpi file onto the Tools/Add-ons window).

Once the crawler is installed, right-click a folder to access the crawler options.