There must be something wrong in my eMClient or my head is bad 
In this account there are messages dating previous years. I read and download all mails, so backups should contain all messages.
I tried also to export received and sent mails of this account (on my laptop), but opening mails they are all from [email protected] - to undisclosed recipients.
Surely because they are not on the server.
I have not this problem with mails I exported 2 years ago from an account which does not exist anymore.
Paul, I thank you very much for your patience. I’ll delete this account from eMClient and will live happy without it (the account).