Expunged message reappeared, giving a new UID

[Γιώργος Δημακόπουλος]

Dovecot 2.2.27

dsync-server(account_name): Warning: Maildir
/usr/local/vhosts/mail/*******/info/Sent: Expunged message reappeared,
giving a new UID (old uid=29787, file=*******)

What triggers this replication for ever ??

Thank you
George