I am not sure that we are understanding "Local Folders" the same way. Local Folders is a structure of folders that is only on your local computer. When you move emails to Local Folders they are only stored on your computer and not on the email server - and it does not matter which email service you used. Local Folders does not need to be associated with any particular email account or service. Is that what you mean? In that case, Local Folder structure won't change at all. It may matter whether you have IMAP or POP setup now. If you have POP, all the emails already downloaded should be saved already in Inbox etc. However if IMAP, you may need to download them for use in 'offline mode' as complete emails to make sure they really are on your computer. If you do want to move emails from the old email account structure to Local Folders to keep them permanently, do so in small groups to begin with. Work up to 200 emails in a batch, or 500 emails if 200 works OK. Do not try to move many hundreds all at once. Be aware the process may take quite some time. Further, to your question, you can have multiple email accounts set up in Thunderbird. So your folders like Inbox, Sent, Trash etc and any subfolder structure you create can exist for each of the accounts that Thunderbird downloads from. You do not need to remove the old account to add a new one. Filtering rules probably will need to set up separately for each account.

Hi Agnes,

You did not answer my question.

You lacked the information regarding my use of IMAP vs POP and the type of device(s) I use to access and store my email.

"Local Folders" = "local folders". Thunderbird has only one set of local folders. Any ancillary accounts appear above the local folders and each is labeled with its email addie and has separate server settings.

I have used POP on a desktop device since 1999. There are no mobile devices involved.

As a result, I have 22 years of email, filtering rules and address book data in my current desktop Thunderbird Local Folders. It's all backed up on an external drive.

My question remains: Will the existing emails and file organization tree within the Local Folders be retained or will these emails, filtering rules and file structure be erased once the new server settings are implemented? I'd like to know prior to purchasing the new email accounts to properly plan for all contingencies.

Another way of putting this is: Will email from the new email address/server settings for the local folder (1) be added to the old email in the various folders within local folders (adhering to the old filtering rules) or (2) cause the old local folder emails, filtering rules and file structure to be erased, resulting in email from the new acct/server landing in the local folders inbox unfiltered with none of the email from the previous old email acct accessible.

PS:

Agnes,

If you cannot state the answer to this, or any, question as a definitive "yes" or "no", your answer should be "I don't know." It's okay not to know an answer.

On viewing your profile, Agnes, I noted that of the 613 questions you've responded to, only 78 have received a "solved" rating. This is a 12.7% success rate, or an 87.3% failure rate depending on how you like to view things.

My recommendation is that you learn to define and request what additional information you need to provide a succinct and definitive answer, wait for a reply, and respond only to the newly delimited situation.

There are not too many people who check scores when volunteers help them, but as you do, know that a lot of people never come back to mark a question as Solved. I will leave your question to someone else.