strange difference between master and replica account

[Marcus Schopen]

Hi,

another problem on another account: on the master on the file system
there is an IMAP account with about 6000 mails inside its INBOX (~ 5,8
GB account size). Connecting with an IMAP client shows 60 mails and an
"unexpunge -l" shows 400 delete mails in the INBOX. 
 On replica side the INBOX there are exactly and only those 60 INBOX
mails and exactly the 400 deleted mails, which seems to be correct (~
2,8 GB account size). sync_client doesn't show any errors and from what
I see using an imap client, master and replica are in sync. But why are
there about 5500 mails on the master inside the INBOX on the filesystem,
so there is a difference of 3 GB between the two INBOXes on filesystem?
Shouldn't those mails have been deleted?

Ciao
Marcus