Hello folks,
Everything was going find until yesterday morning, the sever crash, so i restart the server and two or three hours later, the server crash again. No one was able to connect on zimbra, in my mail.log i got this kind of error, a lot and a lot of this error :

zimbra postfix/smtpd[16131]: connect from unknown[]
zimbra zmmailboxdmgr[25340]: status requested
zimbra zmmailboxdmgr[25340]: status OK
zimbra zmmailboxdmgr[25404]: status requested
zimbra zmmailboxdmgr[25404]: status OK
zimbra postfix/smtpd[16131]: lost connection after DATA from unknown[]
zimbra postfix/smtpd[16131]: disconnect from unknown[]
zimbra postfix/smtpd[16561]: connect from mx2.mail.account.com[]
zimbra postfix/smtpd[16561]: disconnect from mx2.mail.account.com[]
zimbra postfix/smtpd[16140]: connect from mail35.elabs3.com[]
zimbra postfix/smtpd[16151]: connect from unknown[]
zimbra postfix/smtpd[16147]: lost connection after DATA from unknown[]
zimbra postfix/smtpd[16147]: disconnect from unknown[]
zimbra postfix/smtpd[16151]: warning: hostname verification failed: Name or service not known
zimbra postfix/smtpd[16151]: connect from unknown[]
zimbra postfix/smtpd[16151]: NOQUEUE: reject: RCPT from unknown[]: 550 5.1.1 <bridwell@my.account.com>: Recipient address rejected: my.account.com; from=<mtg@boldopinion.com> to=<bridwell@my.account.com> proto=ESMTP helo=<[]>
zimbra postfix/smtpd[16151]: lost connection after DATA from unknown[]

And two or three hours later... i restart zimbra with this command :
su - zimbra -c "zmcontrol start"

and i had this :

Starting ldap...Done.
Failed to start slapd. Attempting debug start to determine error.
bdb_db_close: database "": txn_checkpoint failed: Invalid argument (22).
backend_startup_one (type=hdb, suffix=""): bi_db_open failed! (22)
bdb_db_close: database "": alock_close failed

Any hint where i can start my research, anyone can help me to resolve this ?