do you use message filters? Sounds like one no doing what is expected

I am not really sure as the problem appears to have originated on the replyer's end whereby the reply was a reply to an email I sent. And, in addition, to sending the reply to me some how other valid email addresses in my address book were grabbed and sent the reply. Also, the reply was sent to email addresses no longer in use by former or ex-users. I believe there are message or email filters in use. Still a mystery as to how this stuff happens... CZeigler

given your address book is on your computer and there is no connection to Thunderbird once you click send, your assumption is totally wrong as to either where the addresses came from, or how they came to be there.

Thanks for all your efforts and input so far...

I have reexamined the subject email. The response email was dated and sent 4-1-2016 @ 8:34 PM and was only sent to me from JB.

I learned of a subsequent email from JB in response to my original email to JB. It was dated and sent from JB on 4-1-2016 @ 8:48 PM. This email was sent to various email addresses in my address book but not to all the addresses there. This subsequent email was not sent to me. I only learned about it when one of the recipients emailed me saying she received the email. Otherwise I would have never known about this happening nor when and to whom it was sent to.

I am awaiting a call from JB to see what he thinks.

Thanks again. CZeigler

The only way JB could have those email addresses is if you ever sent an email to several people in your address book including JB. So, JB was one of several recipients. Or you sent a 'Forwards' email to JB which had those email addresses in the contents of the forwarded email. So JB could have an old email possibly with several people from your address book in a TO field.

It does not explain how or why JB sent the response to those people.

Possible thoughts on this: If the content of that 8:48 PM email (as received by your friend) seems like a normal response and not something like spam, then somehow JB may have used an old email to try to reply to you, which auto inserted all those addresses. Perhaps JB did not notice this and sent in error, but could not recall the email as it had already been sent, although it would be reasonable to expect your name would still have been in the list of TO email addresses.

If the response from JB, which your friend received seems more like a spam email, it could also be an unknown nefarious person abusing JB's email address and somehow they have gained access to those email addresses. So possibly, JB did not actually send the email.

Hello, Toad Hall, Yes to the only way JB could have those email addresses. I have in the past sent an email to several address book contacts including JB as a recipient. That was the case here in that he was one recipient of 17. However, the other 16 email recipients were sent under Bcc: in the TO: field or undisclosed. So JB did not get those contacts from this particular email since they were undisclosed. As to the explanation of how or why JB sent his response to other people. I do not know a JB is a very opinionated person so he probably wanted to share his thoughts with others. He couldn't share them with the undisclosed. Remember, he sent a reply to me at 8:34 PM with his comments but only to me. But JB obviously had one of my very very old emails with some of the 16 undisclosed recipients in addition to others in the TO field. So he used the old email with my contacts and fired off an email at 8:48 PM to all of those folks. Some of them are dead and some of the email addresses are not viable or have changed. One of the recipients was my friend who alerted me that she had received the message. I think she was concerned as she does not know JB. Remember I had no knowledge of JB's email to all the others as I was not copied. So once I put 2 and 2 together I contacted Mozilla with my question and you were spot on in answering it. I will no longer send JB emails since he seems not to have a moral code and an issue with ethics. Thanks again and have a great day. CZeigler