That feature is already in the message view pane and in message list pane.

ETA? It's a frustrating noticeable, measurable, rudimentary omission. Is an on/off text Event somehow nontrivial?

The snipping program removes the pointer, which indicated the selected message's Sender Name. No email address displays onHover.

What is it that you are not seeing?

When in my Microsoft email account, I can hover my cursor over a sender and the entire email address with name, @, and domain show up. In Thunderbird, nothing. The only way to see what the complete address is, is to open the email. I do not want to open spam/junk/phishing/etc as that will let the sender(s) know they have a valid email to try and exploit. I find those types of emails and send them straight to junk and then empty the junk folder. Never opened/no response means eventually they will move onto someone else.

I do not want to open spam/junk/phishing/etc as that will let the sender(s) know they have a valid email to try and exploit.

Absolutely incorrect when using Thunderbird.

A very popular misconception which has it's origins in the automatic display of images in email bodies and the use of web bugs (1 pixel transparent images) in email to determine if the message is read. Particularly relevant in mail products that appear to lack the control over remote images Thunderbird has. Products that they always show remote images will load these web bugs. My email from Ebay is full of them, as is mail from most US based companies. Ebay even offered to discontinue email from my saved searches because I did not read them, the bugs are so integrated into their marketing processes.

Thunderbird does not load remote images in mail marked as junk for exactly that reason. What is an essential feature in a Microsoft product because it encourages web bugs by it's convenient design, serves no real purpose in Thunderbird because Thunderbird has addressed the issue with privacy in mind by not even loading the images.

What is it that you are not seeing?

+1 to OP, a label of the sender email address while in list view. It's something I rely upon b/c of a disability. If I don't use a webpage, I need to use Mailwasher, which is great for header data but has its own usability challenges.

See this screen snip for an example.

Mr Matt:

The messages that are in the Junk folder are not the ones that I have...doubts about. It is the ones in my Inbox that I do not recognize that are at issue. Being able to see the entire username/domain address header is helpful. I can then report the username as junk/spam/phishing, as well as the domain. And block under both the user and the domain.

Use this add-on to show the address as a column:

https://addons.thunderbird.net/en-US/thunderbird/addon/full-address-column/

sfhowes:

That is a beautiful work around. And more elegant than the hover option. Thank you.