Is it possible there's an address in the list that causes the sending to fail, e.g. a typo or a leading or trailing space? Also, and it may not be relevant, but avoid spaces and special characters in a list name.

There is no phone support. Please edit your post to remove your email address, to avoid spam spiders.

rex_perry said

I have a group of email address, forty in total, with the name "Class 50-100". When I send a message intended for that group, Thunderbird only sends about half. If I send the message to the individual addresses, it seems that things work as they should. There are two other groups, with about the same number of adressees. When sending to those groups everything seems to work fine. What is wrong with "Class 50-100"? Is there a wroking phone number for Mozilla support? Thanks Rex Perry

I did have one name in the list that had parenthesis. Those were removed. I have looked at the list of names and addresses and do not see anything that looks out of place. The email address was removed per your suggestion. Would you explain "leading or trailing space"? I think that means a space between a letter, either beginning or ending. Is that right? I might add that if I enter the addresses individually and not use the group function, the note will work fine. Thanks for your help,

By spaces in a list name, I meant the name of the list itself, i.e. use Class_50_100. A leading or trailing space means a space before or after the email address, which is not always obvious when viewing a contact in Address Book. Contacts are usually added to a mailing list by dragging the contact from the address book and dropping it onto the list icon in the left pane.

Your address still appears in your original post. Click 'Edit this post' next to the post.

I am going to say, at least for now, that this problem is solved. I renamed the groups per your suggestion and that seemed to work on a test basis. Thank you for your assistance, and the prompt responses. R