backupd and sync_client Syntax error

[Marco]

Hello,

  I would ask an help with a new replication error in backup channel.
I have this never-ending loop error:

2020-07-22T11:35:16.212126+02:00 tst-msg03 cyrus/sync_client[22465]: 
MAILBOXES received NO response: IMAP_PROTOCOL_BAD_PARAMETERS Bad parameters
2020-07-22T11:35:16.212185+02:00 tst-msg03 cyrus/sync_client[22465]: 
Error in do_sync(): bailing out! Syntax error in parameters
2020-07-22T11:35:16.212228+02:00 tst-msg03 cyrus/sync_client[22465]: 
Processing sync log file /var/lib/imap/sync/bck/log-run failed: Syntax 
error in parameters
2020-07-22T11:35:16.216962+02:00 tst-msg03 cyrus/sync_client[22465]: 
Reprocessing sync log file /var/lib/imap/sync/bck/log-run


The "log-run" file ends with:

APPEND "example.com!user.gianni^ferromagnetic.  Cartella Molto Spaziosa"
MAILBOX "example.com!user.gianni^ferromagnetic.  Cartella Molto Spaziosa"
MAILBOX "example.com!user.gianni^ferromagnetic.  Cartella Molto Spaziosa"
APPEND "example.com!user.gianni^ferromagnetic.  Cartella Molto 
Spaziosa.Sottocartella"
MAILBOX "example.com!user.gianni^ferromagnetic.  Cartella Molto 
Spaziosa.Sottocartella"
MAILBOX "example.com!user.gianni^ferromagnetic.  Cartella Molto 
Spaziosa.Sottocartella"
APPEND example.com!user.gianni^ferromagnetic.10
MAILBOX example.com!user.gianni^ferromagnetic.10
MAILBOX example.com!user.gianni^ferromagnetic.10
APPEND example.com!user.gianni^ferromagnetic.Abbcc
MAILBOX example.com!user.gianni^ferromagnetic.Abbcc
MAILBOX example.com!user.gianni^ferromagnetic.Abbcc
APPEND example.com!user.gianni^ferromagnetic.Abc
MAILBOX example.com!user.gianni^ferromagnetic.Abc
MAILBOX example.com!user.gianni^ferromagnetic.Abc
MAILBOX "example.com!user.gianni^ferromagnetic.Cartella 1"
MAILBOX "example.com!user.gianni^ferromagnetic.Cartella 1"
APPEND "example.com!user.gianni^ferromagnetic.Cartella 1.Cestino"
MAILBOX "example.com!user.gianni^ferromagnetic.Cartella 1.Cestino"
MAILBOX "example.com!user.gianni^ferromagnetic.Cartella 1.Cestino"
APPEND "example.com!user.gianni^ferromagnetic.Cartella 1.Cestino.Test"
MAILBOX "example.com!user.gianni^ferromagnetic.Cartella 1.Cestino.Test"
MAILBOX "example.com!user.gianni^ferromagnetic.Cartella 1.Cestino.Test"
MAILBOX "example.com!user.gianni^ferromagnetic.Cartella 1.Spam"
MAILBOX "example.com!user.gianni^ferromagnetic.Cartella 1.Spam"
APPEND "example.com!user.gianni^ferromagnetic.Cartella 1.ma,cia"
MAILBOX "example.com!user.gianni^ferromagnetic.Cartella 1.ma,cia"
MAILBOX "example.com!user.gianni^ferromagnetic.Cartella 1.ma,cia"
MAILBOX "example.com!user.gianni^ferromagnetic.Cartella 1.ma,cia.Archivio"
MAILBOX "example.com!user.gianni^ferromagnetic.Cartella 1.ma,cia.Archivio"
APPEND "example.com!user.gianni^ferromagnetic.Cartella Spaziosa"
MAILBOX "example.com!user.gianni^ferromagnetic.Cartella Spaziosa"
MAILBOX "example.com!user.gianni^ferromagnetic.Cartella Spaziosa"

The log-run has the same last-modified date of the first syslog error 
message of syntax error.


Other strange folder names I created are

MAILBOX example.com!user.baraccone.prova:prova:
MAILBOX example.com!user.baraccone.prova:prova:
MAILBOX example.com!user.baraccone.prova^1
MAILBOX example.com!user.baraccone.prova^1


I suspect that some folder name breaks the backup replication...

Thank you very much

Cheers
Marco