mail logon error after samAccountName change

Hi,

I'm working on an Active Directory migration and we are changing all users samAccountNames. I'm having trouble configuring Mac OsX (10.6.8) mail application (4.6) after samAccountName change. In mail configuration I have changed username in account Tab, but it is not working. I got the conole error:

03/02/15 21.21.33 com.apple.mail[2202] -ERR Logon failure: unknown user name or bad password.

I have also cheked keychain and delete the old entries, but it is still not working

03/02/15 21.37.54 [0x0-0xae0ae].com.apple.keychainaccess[1618] 2015-02-03 21:37:54.041 Keychain Agent[2268:e07] CFPreferences: user home directory at file://localhost/Users/test.sharedz/ is unavailable. User domains will be volatile.

03/02/15 21.38.12 com.apple.ReportCrash.Root[2272] 2015-02-03 21:38:12.045 ReportCrash[2272:1407] Saved crash report for Keychain Agent[2270] version ??? (???) to /Library/Logs/DiagnosticReports/Keychain Agent_2015-02-03-213811_localhost.crash

03/02/15 21.45.03 Mail[2279] /SourceCache/Message/Message-1085/Authentication.subproj/GSSAPIAuthentication.m :262 Kerberos helper status = 0, major status = 851968, minor status = 0

Any Idea?