hi here i am using postfix on Centos 5.5. Squirrelmail is working fine except password is not changing from webmail "change password" plugins. Getting like error "--> 500 Old password is incorrect.” But password is ok. Please give some idea regarding above problem, it will be very helpful for me. Please if possible give me solution

Here i am using postfix on Centos 5.5. Squirrelmail is working fine except password is not changing from webmail "change password" plugins. Getting like error "--> 500 Old password is incorrect.” But password is ok. Please give some idea regarding above problem, it will be very helpful for me. Please if possible give me solution