I guess you are talking about the header info. Go the the View menu and set Headers to Normal instead of All.

I have never seen network password represented there.

Thank you for the reply and for looking into my problem. View was not set to "all". It appears more as a 'footer' than a header if you will. Network name and password were listed as well as the IP address of all computers that use the network. It is exactly the "status" setup page of the modem with all it's properties. Any suggestions?

gratitude

The signature is placed at the bottom of a message. I would check to see if something got added there. I am on a Android device so I cannot look right now but I think it is Account Settings-Composition where the signature window is.

Thank you for that suggestion. I never changed my settings, never used a signature, and the added nfo I'm reporting shows up in received messages that were original, i.e. not replies or threads and did not originate from my computer, domain, etc.

My ISP and my domain host have run through all options and they point to a problem with Thunderbird since the same domain using a webhost and my other e-mail accounts on the same computer using other hosts do not have this problem. I have run a virus scan with a clean result, I am up to date on the Thunderbird version. Thunderbird is accessing some information in my computer about my network that is not current since going through a tech support session with my ISP. Where would that information be stored &/or why is Thunderbird accessing my modem information at all? Thanks kindly for continued problem solving solutions.

Is this info visible when you view the message in the Sent folder?

Thunderbird does not access modem or network info. It just knows if you have an Internet connection so it can stay online and send and receive. If it does not see that connection it goes offline.

I sent a PM to another volunteer to take a look at this and see if he has any ideas.

I would still like to know if this info is on the saved message in the sent folder

The nfo is indeed in the saved messages in the sent folder that were replies to incoming e-mails that had the appended info from before I saw the unwanted info. The info is attached to incoming e-mails you see. That is part of what is so confounding about it. Thank you for your help.

I'd say it's a problem with the router. It's volunteering all this info apparently without challenging the authority of whoever or whatever is asking for it.

I have seen discussions revolving around the observation that Thunderbird includes some local information such as the host machine's local IP address, and usually the routers's internal IP address. The overly cautious would argue that such data might be useful to anyone trying to analyse and break into their system. And this leads on to a discussion about how to set it to say something less helpful to a would-be intruder, and arguments over interpretations of the relevant RFCs and whether or not Thunderbird should include this data in the first place.

https://bugzilla.mozilla.org/show_bug.cgi?id=497901

Anyhow, this is anecdotal evidence suggesting that Thunderbird does strike up a conversation with the router to elicit some of the routeing data. It seems that when questioned, your router is singing like a canary.

Most email clients do not include this stage of the routeing information, so you might be an example of a rare combination of using that particular router along with Thunderbird as the email client. Users of other email clients (and specifically, webmail) would probably never see this information.