Send an email to a group excluding a member in Thunderbird

The Thunderbird 1.5 - 2.0.0.* add-on called NotTo-say will do what you want. NotTo, as the title says, enables you to avoid sending mail to specific recipients.

https://addons.mozilla.org/en-US/thunderbird/addon/4935/

The extension works in two levels:

1. When you compose the mail you can mark an address to be NotTo address by selecting "NotTo" from the drop down box next to the addresses box. When sending the mail, it won't send to the addresses you've specified. This is useful when you have a mailing list containing a lot of recipients and you wish to avoid sending the mail to specific individuals.
2. A new forward command is added to the forward menu button: "NotTo Forward". It acts as a regular forward, but in addition puts the sender in a NotTo address. This is useful when you want to forward a mail to a mailing list (like friends) which includes the original sender. You wouldn't want sending the mail back to him/her.

Acknowledgments goes to Noa Rotstein for this idea.

I don't know of any client that does this. You could always make some groups like friends-notbill and friends-notbillorted, but that is hacky and would lead to needing a lot of maintenance.