Urgent help with moving files from an old roundcube to the newest one

[camprut]

I have a big big problem. I was using an old Roundcube on my previous server and now I am on Synology NAS. I have put emails in folders subfolders structure and I need to move to the new machine. The biggest problem is that folders in my old machine are structered like that:
Folder Administrator-
       subfolder Customers and inside a lot of emails
       subfolder  Letters and inside a lot of emails
        subfolder Computers and inside a lot of emails

Folder InternetAddresses and inside a lot of emails

Now I copied all files from the old server to my HDD. And I can see in the structure is like this:  Folder Administarator and inside files: Customers, Letters, Computers

File  InternetAddresses 200MB big

This does not correspond to the new Roundcube file structure - WHEREVER I PUT InternetAddresses file OR files Customers, Letters, Computers THEY ARE NEVER VISIBLE BY THE NEW ROUNDCUBE. I have many folders that it is impossible to sort this manually. The newest roundcube is NOT expecting FILES.

When I put the file InternetAddresses into TESTFOLDER-cur  it is visible as an email with a subject Don't delete this messages -folder internal DATA and it is a text file with all my emails and mime attachements inside.  THOSE FILES SHOULD BE SET OF EMAIL NOT ONE FILE

PLEASE HELP

[JohnDoh]

Hi. This is not a Roundcube issue. Roundcube is an IMAP client. It has no directly relationship to the email files themselves stored on your server. Managing that is the job of your IMAP server. Migrating between IMAP servers can be trickey but I think most have insturctions on how to do it and a quick search suggest that Synology is no different, see https://www.synology.com/en-uk/knowledgebase/DSM/tutorial/General/How_to_migrate_emails_from_other_mail_servers_to_Synology_MailPlus_Server

[camprut]

Hi John it was very helpful. but I have DS216Play
Is there a way to install a MailPlusServer I have Mail Server only.
iS there another option to convert this mail? I have my folders on my HDD

thank you

[JohnDoh]

the synology community would probably be a better place for questions like that