KMail 5.3.2 does not copy files from offline IMAP

Hi,
I have an inactive mail account where I need to save the mails for documentation purposes.
It was a IMAP account that was fully synced with KMail - the server is not live anymore, but I can read the mails. I noticed some mail content seem to be missing (maybe a consequence of the restore from a backup)

Now I want to back it up to an active Mail account. KMail issues an error message: Unable to retrieve item from resource: Das Element kann im Offline-Modus nicht geholt werden.

Saving the folder locally does not work for the same reason.

Any idea for a workaround (except copying each individual mail)?
Thanks in advance!

In general,
IMAP differs from other protocols (like POP3) in that the messages are largely stored on the Server only. Headers are downloaded initially, and the bodies are downloaded only when explicitly requested.

Therefor,
I don’t know that there is really a good client-side backup method when your mail is IMAP.

So,
Option 1.
It’s very common to switch to POP3 to ensure that the client downloads every message and stores a copy locally. You’ll also be able to read messages offline for this reason.

Option 2.
Set up another mail server and forward a copy of your messages to that mail server.

AFAIK,
TSU

The KMail setting ‘Download all mails for offline usage’ should exactly do that…

Therefor,
I don’t know that there is really a good client-side backup method when your mail is IMAP.

Option 1.
It’s very common to switch to POP3 to ensure that the client downloads every message and stores a copy locally. You’ll also be able to read messages offline for this reason.

That may work well if the original mail server is still alive…which is unfortunately not the case anymore

Option 2.
Set up another mail server and forward a copy of your messages to that mail server.

Good idea as well. But it asks again to wait until the transfer is completed…(which will of course not happen)

Did you try kMail’s import function?