In 'Account Settings' Bottom of left Pane - Local Folders Is the 'Local Folders' mail account still called 'Local Folders' or has that name been changed to 'Ralph Office'? If it has been changed to 'Ralph Office' then rename it back to 'Local Folders'.

Is the account an Imap account or a Pop account ?

If Imap: In Account Settings for the mail account select 'Copies & Folders' Select 'Other' and choose 'Sent on account name'

Exit and restart Thunderbird.

• Local Folders is the name.
• It is an IMAP account.
• I have done: Select 'Other' and choose 'Sent on account name'

That appears to have worked, thank you, although so far only with an email to one of my other accounts. Tomorrow, I'll check with an email to another person/email address.

Unfortunately, after I have now sent an email to another person/email address it still ends up in the Local Folders Sent folder. So problem is not solved.

I have solved the problem by setting up a Message Filter to automatically move emails from the Local Sent to the Account Sent folder. That works OK, but does not explain the underlying problem. I did move some emails from the Accounts folders to the Local folders, so maybe that has upset things?

Are you using an addon like 'Identity Chooser' ?

Does the 'Ralph Office' mail account have more than one identity ?

This is what I believe is occuring. If using a From email address which doesn't match the email address for the default identity stored for the account, then Thunderbird is defaulting back to "Local Folders"

In Account Settings As you have altered the default Account Name from the email address to 'Ralph Office'

• Select 'Ralph Office' account name in left pane.
• On the right you will see the 'Email Address' for that mail account. Note that email address as it should be the same as used in the outgoing smtp server which we will check shortly.
• click on 'Manage identities' button

You should see at least one and it should be the same email address as the account and it should be set up as the default. Confirm the default identity is the email address which that mail account was set up to use when created.

How many identities do you see?

Now I need you to check to see what outgoing smtp server that account is using. I need you to do this in a specific way to ensure you do not end up editing the wrong smtp server. Do NOT click on the 'Edit SMTP_Server' button.

• In Left Pane - scroll to the bottom - below 'Local Folders' is 'Outgoing Server (SMTP)'
• click on 'Outgoing Server (SMTP)'

It will show a list of all your outgoing smtp servers. As you have four mail accounts there should be four outgoing smtp servers. One for each mail account.

• In list, Select each in turn until you locate the one that has the 'User Name' which is the same email address as used by 'Ralph Office' account
• Click on Edit
• Description: Please type the email address as shown in the User Name = same email address as account - then there is no confusion
• Click on OK

Now to check the Ralph Office account is actually sending using it's own smtp server.

• Select 'Ralph Office' account name in left pane.
• Look bottom right for 'Outgoing Server SMTP)

This is where that 'Description' field comes in handy as it will now display the email address.

• Click on the drop down options and select the correct one - where email address matches the one the account is using.

Exit Thunderbird and wait a few moments for background processes and file updating to complete. Start Thunderbird.

Thank you for further info on this problem. In answer to your questions and suggested actions:

1. Are you using an addon like 'Identity Chooser' ? NO

2. Does the 'Ralph Office' mail account have more than one identity ? YES, there are 4, each with its own name set via an email forwarder.

3. As you have four mail accounts there should be four outgoing smtp servers. One for each mail account. NO, there is only one as each account is with the same ISP. (see attachment)

4. Description: Please type the email address as shown in the User Name = same email address as account - then there is no confusion . THE DESCRIPTION is just the name of the provider. As there is only one SMTP I don't ant to change it to a single email address.

5. Now to check the Ralph Office account is actually sending using it's own smtp server. AS THERE IS ONLY ONE SMTP there is no choice

So that does not seem to solve anything. Indeed why has the problem suddenly started on this account? It did not happen before and it does not happen with another account which also has multiple identities.

You can still set up separate smtp because there are different email address which ideally would have different passwords if you were to access them via the webmail account.

It seems you are not sending anything securely. I presume you are using an active Plusnet broadband account which means it's not as important to authenticate, but that does not mean you cannot.

Plusnet do recommend using the secure method :

• Server name: relay.plus.net
• Port : 587
• Connection Security: STARTTLS
• Authentication Method: Normal Password
• User Name: full email address

• https://www.plus.net/help/email-guides/how-to-set-up-plusnet-email/

TEST: Thunderbird is defaulting to Local Folders because you are using a From email address which doesn't match the email address for the default identity stored for the account.

Temporarilly - disable the Message Filter.

In Account Settings

• Select 'Ralph Office' account name
• Click on 'Manage Identities' button
• Choose one of your identity email addresses and set it as default. then click on OK.

• Click on 'Write' to open a new window
• Then try sending an email but 'FROM' must be the whatever identity/email address you have set as default.

Where is the saved sent email ?

Repeat the above to set another identity/email address as default. then send again but make sure you send using whatever identity email address you have just set up as default. Where is the saved sent email ?

Thank you, Toad Hall. I have changed the Plusnet SMTP settings as you suggest.

Re the Account Settings, the email address is already set to the default email address for that account. In fact as I mentioned, the other accounts are set up in exactly the same way, one with three identities, and all work OK, as did the office account until a few weeks ago.

However, as a result of looking at the account settings for each identity, I have discovered the problem. Although the settings were correct for the default account/identity I found that for the other identities the Sent folder had become set to Local folders. Why this has happened, I have no idea. But thank you for your help in looking into this matter and eventually getting to the source of the problem.