Apple Mail sending mail from wrong account

Yep, that's what I think it does. I am pretty sure I used to have "best" checked, but changed it due to this very problem, perhaps a year or two ago. But recently it did it again. I can't seem to find any official explanation of these settings, but my own personal view based on my experience (over quite a few years) is that all settings are completely ignored if SMTP server fails, and Mail just automatically overrules and decides to find another server to get the mail sent asap. Nice, some would say. Not nice, I would say. :)

thanks again, if anyone happens on this thread and knows the real answer, or how to prevent Mail using any SMTP servers except the chosen one (or the one matching the incoming account and no others), please drop a note here!

Thanks for replying.

That shows my icloud account but it's not relevant here as that box only relates to sending new emails, so it chooses the default account for any newly composed email. I am talking about replying.

So if you email me from BDA@icloud.com, you address the email to joey@carsales.com. I receive it in my aggregated inbox for all incoming mail. If I click reply, it will TRY to send from the SMTP server details which are on the joey@carsales.com emaill account in my account settings. BUT - if that server fails to respond in time or for whatever reason it doesn,t go through, the email pops up again out of my outbox and I click send again. But I recently noticed it had (and does) CHANGE the outgoing server. Basically I think Apple Mail is 'trying to be helpful' but offering an alternative server, but I want to turn this off so it can not happen. Imagine you get a reply to your email about a car, from some guy called joey@pinkdreadlocks.com or even joey.smith@police.uk (!!), it could be rather embarassing for me, and it is!!

I dont think I can see any way to make Mail do it, so I am forced to either pay for a client which does, or do something which seems a bit crazy, like have one user account on my entire machine for each website (5?!) and log out and in constantly all day to check emails from each, which kinda destroys the idea of an aggregated inbox :D

I have the option for "automatically choose best account" (who defines best?!) and a list of about 10 options for all my accounts.

But not sure if you got my point.... this option is described as choosing which account to send "New Email" from. I am not having a problemm with new emails, I can choose whenever i compose a new email, or i can let it use mjy icloud, which is fine.

The problem is not when sending new email, its when replying to one which came in.