Thanks for a bug report. I followed the thread [1], I even replied to it [2], and it seems my reply was not done in an understandable way.

The 'Edit as New Message' tries to use the right From account. It's usually one of those in the To/Cc headers. If such configured cannot be found, then the account in which the message is located is used. There is a difference with the On This Computer messages, which doesn't have assigned any account (+/- send account override). In such case, if the From doesn't match any account, it is left as is, which means the From override applies here, and it forces the View->From Override Field to be automatically turned on. This option is only turned on when needed, it's not turned off on its own, it's left up to the user whether it should be off.

I didn't get why you use the Edit as New Message from the thread [1], if it's some sort of Reply, then I agree with the folks there that it's a misuse of the feature. Reply is reply and Edit as new message is edit as new message. Those are two very different things. I'd need to know your use case in more detail to eventually suggest you better way to achieve what you are trying to achieve by using this Edit as New Message.

I know Andre sent you to the distributio bug tracker, which makes sense for versions obsolete by upstream (upstream is able to take care of one stable release series only, due to limited man power), unless the problem is reproducible in the latest stable version. I am able to reproduce this with the current development version, that's how I found the behaviour for the On This Computer folders/messages.

I do not want to force you to file bug in another bug tracker, first - it feels lame action from my side; second - I'm not sure what should be changed here, because the Edit as New Message is a special feature.

Even I'm closing this now, I'll be happy to discuss possibilities with you here (we can discuss in closed bugs as well), especially if you are willing to describe your use case, thus we could either find a different way to achieve the same or we'd consider some way to make Edit as New Message work somehow better (also in your use case).

[1] https://mail.gnome.org/archives/evolution-list/2019-October/msg00004.html
[2] https://mail.gnome.org/archives/evolution-list/2019-October/msg00024.html

Hi Milan,
thanks for your detailed comment. Clearly, I used 'Edit as New Message' without too much thinking, and now I understand how to avoid the snafu I made. 
Still, I am not sure to understand every detail of your comments (your first paragraph is obscure to me).  
For the sake of pedantry, let me restate what puzzled me:

Consider the message I just received when you commented my bug report, its main headers are:
From:	bugzilla
To:	*mymail*@*mydomain*.net
Subject:[Bug 1758344] unable to change default for View/'From Override Field'
Date:	Fri, 04 Oct 2019 06:42:23 +0000 (10/04/2019 08:42:23 AM)

Now I decide to 'Edit as New Message' it. In the ensuing composer window, headers are shown as:
From: *mymail*@*mydomain*.net  (selected option of the drop down menu)
Address: bugzilla (this is shown on the right side of the window)
To: *mymail*@*mydomain*.net
(and  View/'From Override Field' is checked)

If I do not erase the Address field, message is delivered with: 
From: bugzilla

Is it so, because 'From Override Field' is checked (by default)? Anyway, I find it confusing, since the account displayed on the From:drop menu is what hits the eye. 
Botton line,  I was confused by to see both a From and an Address field, and I did not guessed that the latter was going to be used for the From field. 

For my use case, it could be that a receive a text from somebody (say a piece of translation, or even lines of code) to edit it, and I want just to edit it and ship back.

(In reply to mario from comment #2)
> Is it so, because 'From Override Field' is checked (by default)?

It is not checked by default, it is checked, because either the previous composer window had it shown when closing it, or because the new message's From doesn't match the one from the used account (it's auto-shown in such cases). The later happens for you. When you turn off the option in the View menu it'll not be used. It's used only when the entries are visible.

You can see that the last state sticks when you make the change, then start a new message or hit Reply. The Edit as New Message causes the change here.

> Botton line,  I was confused by to see both a From and an Address field, and
> I did not guessed that the latter was going to be used for the From field. 

I see, maybe there could be done a better indication why those are shown, though I'm not sure what that would be.

> For my use case, it could be that a receive a text from somebody (say a
> piece of translation, or even lines of code) to edit it, and I want just to
> edit it and ship back.

Ah, okay, so it is a reply. It's better to be a real reply, thus the messages can be tight together (you can see the history when you've Group By Threads enabled), but you do not want to quote the body. It can be confusing (it would be for me for sure, because I'd not see what you changed without reading possibly lengthy document, meaning that I also remember what I wrote before), but it surely finds its use cases. Either you can change reply style in Edit->Preferences->Composer Preferences->General tab from Quoted to say Inline (you can check what each type does), or you can use Message->Alternative Reply (Ctrl+Alt+R), where you can preset what the reply should look like, but only for some messages (the values you change in that dialog are remembered); the idea behind this is that users can use two different formats for the reply without too much hassle. I'm not sure whether it's included also in your version, but I think it is. You can change reply style also per account, in account's Properties->Composing Messages tab, thus the global setting can be different from what the account usually uses and from what the Alternative Reply uses. I mean, these things can be fine tuned a bit, to make often actions simpler for the user.

(In reply to Milan Crha from comment #3)

> (In reply to mario from comment #2)
> > Is it so, because 'From Override Field' is checked (by default)?
> 
> It is not checked by default, it is checked, because either the previous
> composer window had it shown when closing it, or because the new message's
> From doesn't match the one from the used account (it's auto-shown in such
> cases). The later happens for you. 

does it? *mymail*@*mydomain*.net above is my used account (AFAIK)

> When you turn off the option in the View
> menu it'll not be used. It's used only when the entries are visible.

This is clear. It is not clear, how to open a Composer window with View/'From Override Field' unchecked. 
I get checked even if I open a Composer window by Reply to sender, Reply to all, or Forward. 

> 
> You can see that the last state sticks when you make the change, then start
> a new message or hit Reply. The Edit as New Message causes the change here.

here, it does not stick. 
Please, instruct me on the precise step-to-step actions I need to perform

> 
> > Botton line,  I was confused by to see both a From and an Address field, and
> > I did not guessed that the latter was going to be used for the From field. 
> 
> I see, maybe there could be done a better indication why those are shown,
> though I'm not sure what that would be.

If Address is not empty, From:drop menu should be hidden, shouldn't it? Am I missing something here? 

> 
> > For my use case, .....
....
> you can use
> Message->Alternative Reply (Ctrl+Alt+R)
Yes, this is that! (inline). I was not aware of it. 

thanks

(In reply to mario from comment #4)
> > The later happens for you. 
> 
> does it? *mymail*@*mydomain*.net above is my used account (AFAIK)

I guess so from your description at least.

> It is not clear, how to open a Composer window with
> View/'From Override Field' unchecked.

It's because it's remembered from the last composer window. Try this:
a) in menu File->New->Mail Message (Ctrl+Shift+M)
b) in there click menu View->From Override Field to uncheck it
c) close composer (Esc)
d) open composer as in a) - the From override fields are not shown
e) close composer (Esc)
f) reply to a message (Ctrl+R) - the From override fields are not shown

In other words, the From Override Field is shown based on its state the last time the composer was opened, or it's forced to be shown, like when using Edit as New Message in folders under On This Computer (and no Send Account Override is used).

> If Address is not empty, From:drop menu should be hidden, shouldn't it? Am I
> missing something here? 

No, it should not be hidden, you still need to tell the Evolution which server to use to send the message. The From Override Fields are there to pretend that you send as someone else. The original intention was to allow people to use it for temporary changes, like when they use user+bugzilla to know from where their address had been hijack.

By the way, servers are usually configured to reject sending as someone else (according to my experience), though your server doesn't seem to be configured that way.

(In reply to Milan Crha from comment #5)
> (In reply to mario from comment #4)
...
> 
> > It is not clear, how to open a Composer window with
> > View/'From Override Field' unchecked.

.....

On my machine
  a) in menu File->New->Mail Message 
  b) in there click menu View->From Override Field to uncheck it  (Ok)
  c) close composer (Esc)
  d) open composer as in a) - the From override fields are not shown (Ok)
  e) close composer (Esc)
  f) reply to a message (Ctrl+R) - the From override fields are not shown (Ok)
  g) Edit as a New Message - the View->From Override Field is shown checked  (my initial case)

> 
> In other words, the From Override Field is shown based on its state the last
> time the composer was opened, or it's forced to be shown, like when using
> Edit as New Message in folders under On This Computer (and no Send Account
> Override is used)

I am not still sure about this last point

> 
> > If Address is not empty, From:drop menu should be hidden, shouldn't it? Am I
> > missing something here? 
> 
> No, it should not be hidden, you still need to tell the Evolution which
> server to use to send the message.

OK, I got the point. 

.....

> By the way, servers are usually configured to reject sending as someone else
> (according to my experience), though your server doesn't seem to be
> configured that way.

Indeed, I assumed that, and did not care too much, my fault. 
Thanks Cheers

(In reply to mario from comment #6)
>   g) Edit as a New Message - the View->From Override Field is shown checked 
> (my initial case)
> 
> > 
> > In other words, the From Override Field is shown based on its state the last
> > time the composer was opened, or it's forced to be shown, like when using
> > Edit as New Message in folders under On This Computer (and no Send Account
> > Override is used)
> 
> I am not still sure about this last point

The above is expected behaviour when certain conditions are met. I tried to describe them in the middle paragraph (starting "In other words"). I'm afraid I'm not able to rephrase it in any better way, I'm sorry.

> > By the way, servers are usually configured to reject sending as someone else
> > (according to my experience), though your server doesn't seem to be
> > configured that way.
> 
> Indeed, I assumed that, and did not care too much, my fault. 

No no, I didn't mean it as your fault. It was just a side note that some servers would notify you when doing something suspicious (such technic can be used by spammers, thus servers disable them), thus you could notice it easily. Regular users cannot influence what the server does, that can do the admins only.