Cache IOERROR

[Marco]

Hello,

  I have a folder with a tons of mails.
I see this error in log:

Apr  1 08:58:36 tst-msg01 cyrus/squatter[31354]: IOERROR: offset  
greater than cache size
Apr  1 08:58:36 tst-msg01 cyrus/squatter[31354]: IOERROR: invalid  
cache record for uc.test.it!user.utente^101.Archivio.2015 uid 73308  
(System I/O error)

Cyrus-imapd-2.4.17.

This is the cyrus.cache file:
-rw------- 1 cyrus mail 28086238660 Apr  1 09:15 cyrus.cache

I'm trying to delete and rebuild the cache file. But... is there a  
limit in number of mails that a folder can contains?

Thank you very much
Marco