We cancelled an account with a server provider and of course lost some e-mail addresses. For example firstname.lastname@example.org It was configured in TB as a POP account, and outgoing as SMTP.
The Thunderbird setup is running 20+ accounts, so any solution needs to be account specific and needs to include a reasonable method on how to still access all e-mails. Presently running Thunderbird 68.8.0 on Win 10 Pro 64bit with all updates.
Now I am afraid that if I just select the corresponding account in Thunderbird and go "Account Actions" > "Remove Account" it might delete all the e-mails which came through this account over the years. I need to keep those for several years for legal reasons. Since this is part of my production machine, I cannot just do some tests through guesswork.
The setup is such that under "Copies & Folders" the "sent" and "archives" and "drafts" and "templates" are each stored under their respective folder under email@example.com.
I have searched through Mozilla Thunderbird online help on how to remove an account while keeping mails and did not find any entry.
I am willing to do all the needed work, even manual clicking-party, like archiving all mails, if I find a way to keep them separate from all other accounts and keep their structure intact. They must not be mixed or stored under another account.
I tried as a hack to just empty the box for "Server Name" but Thunderbird does not accept an empty box there. So de-activating the account would be just as well as deleting it, if possible.
Since I have 20+ accounts, I often use the feature "get all new messages" and this old account keeps (of course) giving me error messages that are annyoing and pointless.
I could use a dummy or testing domain to fill the Server Name box, but would need one that is specifically provided for that purpose to not receive more error messages and to not anger any other domain holder. I vaguely remember that there used to be private top level domains (for example .zz) for testing or internal purposes (like we all use internal private IP numbers) but cannot find documentation for this, even after plenty searching today.
(I tried to keep it simple but have in fact several such accounts that need this treatment: de-activate account but still keep the mails together respectively. So any input muchly appreciated, thank you.)