1. The ".mc" file is in /usr/newconfig/etc/mail/cf/cf/generic-hpux10.mc. You don't usually use this file in HP-UX. This file is used as a source to compile and create the /etc/mail/sendmail.cf file. Typically this is done by people that are very experts in sendmail. In HP-UX the sendmail customization is done by changing settings in /etc/mail/sendmail.cf.
> And the domain name of the mailserver. after configuring this, the from address will be like "senthil@hp.com" other wise it be "senthil@mail.hp.com"
This can be done in sendmail.mc but also in sendmail.cf by setting the "DM" option as "DMdomain.com"
2. The sendmail "access" database is available, you have to enable it and create the file.
For a lot more details and other info look at
http://www.docs.hp.com/en/5991-6611/5991-6611.pdf