the MX records created under DNS Manager in ISPConfig2 web interface system are similar as below:
MX 10 ispconfig.smartracksolutions.info.
webmail MX 20 ispconfig.smartracksolutions.info.
MX 30 webmail.smartracksolutions.com.
i just changed other settings as well, e.g. ns1.smartracksolutions.info -> ispconfig.smartracksolutions.info, ns2.smartracksolutions.info -> ns0.smartracksolutions.info. you can test "dig webmail.smartracksolutions.com" later to see any difference.