No. But…

You can add multiple addresses to one line, laboriously by hand, but doing so breaks all the autocomplete and address checking. Separate them by commas, and type (or copy-and-paste) accurately.

IIRC you can also multiselect contacts in the Contacts Sidebar and then drag-and-drop them all into one addressing box.

Beware; if you hit <enter> Thunderbird will parse them into its preferred one-per-line format.

I read that a re-work of Thunderbird might incorporate what you are asking for.

What is it about separate lines that your end user finds objectionable? Are they aware that they can move the splitter between addressing and message text boxes to make room for more addresses to be shown?

My name is Sam. I love Mozilla and have since high school when I helped QA an obscure bug affecting my machine. (This was for the Mozilla release, the one now called Seamonkey.)

My user and indeed most users I tech support for is a beginning computer user who "wants things like they used to be" which was Outlook Express originally on XP. However every other mail client agrees with Microsoft's convention.

I will add that I noticed that typing with a , broke autocomplete/spellcheck. I would regard that as a bug. Also, while I was in high school, I needed a mail client that supported encryption, so I switched to Thunderbird and I don't remember it being formatted this way. Did this happen at a specific point in development?

I hope the brain dump helped. And thank you. I do not mean to come across as anything else but kind. I am in the middle of a major Drupal project, so brain is a whirring.

It's not a fault but a deliberate design choice. Since "every other email client" does it all on one line, you shouldn't have trouble finding an alternative email client. For now, you or your users have to accept that this is how Thunderbird works, and this is how it is intended to work. There is a bug open for this on bugzilla; by all means add your vote for it.

Thunderbird has never, as far as I am aware, worked with multiple addresses on one line.

ok. you have been very helpful. what is the number of the bug in bugzilla?

also, I am not trying to be difficult here.

I would add that there aren't that many mail clients around anymore. I mean ideally you want to find something that is pretty open, so you can get the data in and out.

I'm sorry if I came across differently than I intended.

--Sam

also, what's the name of the other program that's based on thunderbird that has this changed.

https://bugzilla.mozilla.org/show_bug.cgi?id=392932

https://bugzilla.mozilla.org/buglist.cgi?bug_id=376583,395606,440370,544347,634255

In many cases, when someone posts "Why doesn't Thunderbird do (name some feature) like (insert alternative email client) does it?", the immediate response that comes to mind is "Why don't you just use that other email client?" Of course here if we're comparing with a defunct email client such as Outlook Express, that option isn't open. But if all email clients looked and worked the same, we'd only need one mail client. Then it wouldn't have any competition and no impetus to improve or fix it. So it's good that we still have a few different and competing clients.

I am not familiar with other programs based on Thunderbird's code. There are some (e.g. Postbox, but my interest wanes at the "buy now" point in the website) but I can't think I have used them. Seamonkey is a close relative but I can't feel comfortable with it.

One which is similar, and uses the same "one address per line" convention is Claws, formerly Sylpheed, but it is not appropriate to the mass audience as it doesn't compose HTML formatted messages, and only reads them courtesy of an add-on.

For myself, I like to have a client that's available on both Windows and Linux. That limits the choice somewhat and pretty much always rules out these "me too" Thunderbird clones.