Thanks Zhang,

i always use it but i see the lbdata1 is very huge about 44GB,i emptied quarantine table data which was 38GB and msg table data which was 4GB large but still i  see no difference .

drwxr-xr-x.  8 mysql mysql 4.0K Jul  8 10:46 .
drwxr-xr-x. 24 root  root  4.0K Feb  6 17:47 ..
drwx------.  2 mysql mysql 4.0K Jul  7  2012 amavisd
-rw-rw----.  1 mysql mysql  44G Jul  8 11:11 ibdata1
-rw-rw----.  1 mysql mysql 5.0M Jul  8 11:11 ib_logfile0
-rw-rw----.  1 mysql mysql 5.0M Jul  8 10:34 ib_logfile1
drwx------.  2 mysql mysql 4.0K Sep  5  2011 iredadmin
drwx------.  2 mysql mysql 4.0K Sep  5  2011 mysql
srwxrwxrwx   1 mysql mysql    0 Jul  8 10:46 mysql.sock
drwx------.  2 mysql mysql 4.0K Jul  8 10:47 policyd
drwx------.  2 mysql mysql 4.0K Sep  5  2011 roundcubemail
drwx------.  2 mysql mysql 4.0K Sep  5  2011 test

I have tried to remove via command line manually but  no row is affected,it is like the quarantined mails no longer exists

mysql> DELETE FROM msgs               WHERE content IN ('S', 's', 'V', 'Y')               AND quar_type IN ('Q', 'F')               AND time_num < UNIX_TIMESTAMP(DATE_SUB(NOW(), INTERVAL 7 DAY));
Query OK, 0 rows affected (0.00 sec)

Thanks for your reply,i truncated all the sql tables in amavisd database as per your suggestion and restarted MySQL as well as amavisd but no changes in size i still see /var/lib/mysql taking almost 44gb of space.

45752504        /var/lib/mysql.

ibdata1

-rw-rw----.  1 mysql mysql  44G Jul  8 17:23 ibdata1

Thanks i will try during off peak hours.