Give us something more. It sounds like you get an answer from your mail service provider. One thing that can go wrong is if you have an empty spot in your list, someone without an email address. That will show up as double comma signs in the to-list. Some service provider limit the amount of emails you can send per timeframe. Worst for private account. Google is one.

The problem is that it tries to send the email to the group name, not each individual. This has never been a problem except when it happened a few weeks ago to me and many others. Whilst I am not an expert on computers I think this problem has been caused by a recent Thunderbird update and hopefully, like the last time, someone will correct it.

I still can't send out an email to a named group. I can only send it out by listing the individuals by name. This is not so bad with only four members in the group but I have one group with around a hundred names and I can't copy and paste and bcc as well for all those. The latest email came back with the following reason. 5.1.1 - Bad destination email address 'invalid domain "": no dot found' I asked my daughter if she knew what it meant but she couldn't help. I don't understand why I am the only one with the problem as last time this happened lots of people were affected. I have not changed any of the email addresses or anything else within the group so all the email addresses are there. As I said before, all I can think is that the latest Thunderbird update has affected things and last time this happened I think a new update may have corrected the problem.

I seem to recall there was a problem if the mailing list name had spaces or underscores, but in the meantime you can open the Contacts sidebar in a Write window (F9), select contacts while holding the Ctrl key, then click Add to Bcc: at the bottom of the sidebar. If you have all your list contacts in a separate address book, and select this book at the top of the sidebar, Ctrl-A will quickly select all the contacts. Not as convenient as selecting a mailing list from the sidebar, then Add to Bcc:, but it should work, although the limit on number of contacts per message, imposed by your service provider, still applies.

Thanks once again. As I said before I am not an expert by any means on a computer so if something doesn't work the way it used to I don't usually know the alternatives. One of the addresses in the group I was trying to send does have any underscore in it so maybe that was stopping it going. At least I have an alternative way to send group emails with your help on bcc and this but hopefully whoever makes changes to Mozilla will correct this fault very soon.

Just to clarify, I believe the problem arose when the name of the mailing list had spaces or underscores, not the address of any of the contacts in the list. Right-click a mailing list, Properties, to modify the list name.

Or, perhaps you are experiencing this bug (mailing list within a mailing list).

The mailing-list-as-address-book approach has some advantages, and avoids many of the bugs associated with pure mailing lists, but keep in mind the 60-contact limit.

Whilst I hear what you say, and I do need more time to look through the information you have sent, I have not recently changed anything in my address book or the groups that I have got so I don't understand why me sending emails to groups worked say a week ago and now they don't. I am almost certain that there was a TB update recently so I have assumed the problem is due to that. Does that sound reasonable? What I have got and have had for over a year is a list of all my addresses and then seven groups using a good few addresses from the main list. I must admit that all the group names, including the one that failed to send, has two or more words in it's title and therefore have spaces so I again say 'it used to be ok but isn't now'. Are you saying that I should take out those spaces and see if I can send an email to the group's name? If so, I will have to wait until I have another one to send out or send out a test email.

If you want to revert to the version previous to the most recent release, the installer is available here:

http://ftp.mozilla.org/pub/mozilla.org/thunderbird/releases/31.4.0/

You can install it over the existing TB without affecting your mail and contacts, or anything else in the profile folder, but to prevent automatic updates, adjust the setting in Tools/Options/Advanced/Update.

Or, test to see whether the spaces in the list names are the source of the problem in 31.5. (Create 2 simple lists, each with two contacts, with or without spaces in the list names).

There are several outstanding bugs for mailing lists, so there's no guarantee the name spaces are the only issue in your case.

It must be something else. my list my gnospen.com works and it has spaces, dots and can be a part of an address. it worked both from my isp's mailserver and from gmail

To update my position with this question, I still can't send an email to a named group under my normal settings but if I enable the 'use bcc instead' app, I can. Doesn't make much sense to me when I used to be able to send group emails by the former method and now I can only do it with the latter. Perhaps someone has an answer to that.