Check your address books for an entry with the same name as your mail list. It may have been added accidentally. Remove it.

In address book window, in left column, I have "collected addresses" and below that have different groups, 3 that have the problem and 2 that work correctly. In the column on the right I have email addresses and also all the groups. I selected 1 group that didn't work that was in the right column and deleted it. The entire group deleted. I recreated the group from scratch. Same problem. I right clicked in the column on the right on a group with the problem, then selected write, the send button was NOT grayed out. Strange. Any other ideas? Thanks

Does the name of the group contain special characters or spaces? This might cause problems…

I made my answer simple instead of explaining. Sorry.

Explanation: If there is an address book entry/contact with the same name as the mailing list, when you type in the name of the mailing list in the "To" section of an e-mail, Thunderbird will use the address book entry, not the mailing list.

If you right-click on the mailing list and say "Write", then it will of course use that entry in the To section, because you are telling it specifically to do so.

So please do as I asked, and look for an address book entry/contact that has the same name as the mailing list.

What Onno Ekker says can also apply. If the name of the mailing list contains spaces, or a quotation mark, or any other character than a letter or number, that can cause problems also.

I was using ( ) in the group name. That was the problem. Would never have thought of that. Thanks for your help. Frank

Hi Bruce I was using ( ) in the group name. That was the problem. Thanks for your help. Frank