problem eith db4 delivery database

[RJ45]

Dec 13 10:11:18 iris lmtpunix[15690]: DBERROR: opening 
/var/lib/imap/deliver.db: Cannot allocate memory
Dec 13 10:11:18 iris lmtpunix[15690]: DBERROR: opening 
/var/lib/imap/deliver.db: cyrusdb error
Dec 13 10:11:18 iris lmtpunix[15690]: FATAL: lmtpd: unable to init 
duplicate delivery database
Dec 13 10:11:18 iris master[20540]: service lmtpunix pid 15690 in READY 
state: terminated abnormally
Dec 13 10:11:18 iris lmtpunix[15691]: DBERROR db4: Logging region out of 
memory; you may need to increase its s
ize

I have these problems and I did not figure out how to solve them
lookign in the past threads.
Anyoen has a hint ?

thanks

Rick