Right click the account in the folder pane. select settings Select outgoing server (SMTP) in the list.

Select the outgoing server of your choice as Default as you apparently do not like the one that is set.

Hello, all the accounts are yahoo-accounts, so they use all the same smtp-server smtp.mail.yahoo.com. But, it's true, in the list of outgoing servers the smtp.mail.yahoo.com is listed 8 times, one with the remark (default); so I selected different ones from the list, but the behavior doesn´t change. The reply of an email without a recipient shows a wrong sender and 'reply to' account.

I hope you can give me further assistance

re :list of outgoing servers the smtp.mail.yahoo.com is listed 8 times, one with the remark (default); so I selected different ones from the list,

Each outgoing server will have a User Name = specific email address. Each mail account needs to use the one which has same UserName as the mail account email address.

As all your accounts are yahoo, it is not so easy to differentiate based on the server name. To make life much easier and less likely to select the wrong smtp server.

right click on mail account name and select 'SEttings' then select 'Outgoing server (SMTP)'

You will see a list of smtp outgoing servers. Select each one in turn and click on 'Edit' For 'Description' type something more meaningful. eg: Personal, Business or first part of email address - the bit before the @. click on OK.

Then select the mail account name in the left pane and at the bottom on the right side, where it says 'Outgoing Server(SMTP)', select the appropriate smtp server from the drop down list. It should be easier to know which is which because you have altered the 'Description' field.

When completed, click on OK to save and close Account Settings.

Then you know that each mail account is using the correct smtp server.

I'm not sure how you received an email if it did not have a TO field, but maybe Matt knows more. Do you mean the received email was sent to you using Cc or Bcc ?

Usually, the TO field will be used to complete the FROM when replying. If Thunderbird cannot located who the email was sent TO, it should then use the default mail account FROM email address. However, you can always select a different FROM from the drop down list prior to sending.

...Select each one in turn and click on 'Edit'.... Sorry that I am taking your time... There is the list of servers, but no edit button or whatever to change them. Thunderbird only allows me to select one in the list, but I don't find how to edit its description.

Yes, there is no recipient, because it was bcc.

You are writing: If Thunderbird cannot located who the email was sent TO, it should then use the default mail account FROM email address. For me, in that case Thunderbird shouldn't take the default account, but the account which received that mail.

There's an edit button here…

You are probably in the right place. Edit is a button on the right side - not on any toolbar.

In the example image below, I have two yahoo smtp servers. So, I edited one Description field so I can which is which. Otherwise they both said Yahoo Mail. If you had several of these. it could become confusing.

The images below should help to explain.

Thank you, I found it. I tried to do it in the account settings, I wasn´t scrolling down enough to see that there is Outgoing servers below the local folders...

So I changed the names, each account has his selected outgoing server, but the behavior stays the same:replying to an email without recipient puts a wrong account into the `From `field. It doesn't put the account to which the email was sent, it doesn't put the default account, it puts the account which is the second in the list (no idea if this helps)... For me the correct behavior would be to take the account the mail was addressed to as ´From` account.

If you need more details to be able to help me - I#ll do everything to provide them

The issue here is I think Thunderbird replies to an email using the identity. when there is no recipient, there is no identity as such to reply with. Hence my suggestion for a change to the default.

The election of an account is complex and I am not sure I really understand it. But my understanding is.

First the account you have selected in the folder pane is chosen. unless you have defined additional identities for that account. In that case the identity selected is based on the identities that have been set up.

The second item is if none of the above work that the "default identity is used. It is also selected if you click a mailto link on a web page for instance.

Have you restated Thunderbird since you changed the default? I would not have thought so, but perhaps a Thunderbird restart is needed for it to take effect.

Are you using the unified folder view or something else. (On the view menu under folders)

Hello, yes, I had restarted Thunderbird , it doesn´t change the behavior.

Here what I did:

I defined my accounts with just the minimum, accepting thunderbirds propositions for pop and smtp-servers. I didn´t define any identities. I just changed the deliveries, so that all incoming mail goes to the local folders inbox. I defined one account as default.

Writing a new mail, thunderbird uses the default account. Clicking on a mailto, thunderbird uses the default account. Replying to a mail which has a receipient, thunderbird uses correctly the account which received that mail in the reply's ´from´and reply-to´field. Replying to a mail which has no receipient, thunderbird doesn´t use the account which received that mail in the reply's ´from´and reply-to´field, but uses another account (all times the same), which is even not the default account.

Let's say, for sure I will live with this, for the rest I love thunderbird, but it's annoying, if I don't pay attention, the mail is sent with an address which the recipient doesn't recognise as mine.

I have no idea if it will really help, but give this add-on a try. https://addons.mozilla.org/en-US/thunderbird/addon/flexible-identity/?src=search

Hello Matt, I tried, but I didn't find a possibility to create a rule, saying:

If there is no recipient

  if it was sent to account1, use account1 as sender
  else if it was sent to account2, use account2 as sender
  else if....and so on....

end

Hope you understand what I want to say

I tried also the correct identity add-on. - same result. Astonishing is that both add-ons offer as default the same (wrong) account which thunderbird is also using; an account which is not default.