I am getting "postfix 500 5.5.2 error bad syntax" and postfix not working....if anyone have idea how to fix it please share..

We are currently running a high production issue in a Sendmail MTA which is using opensource sendmail. The server was crashed due to hardware issue and we are in process of rebuilding the server again. The server was running in a sandwiched mode with IMSS. The sendmail was running with port 25 and 10026 and IMSS was running with port 10025.

We have copied all the files from the redundant server , we are unable to run the sendmail on port 10026. Sendmail failing to startup on port 10026 as custom sendmail startup script (/etc/init.d/sendmail) copied

Error while starting sendmail

server1:# /etc/init.d/sendmail start
Starting sendmail: [ OK ]
Starting sm-client: /etc/mail/submit.cf: line 0: cannot open: No such file or directory

I am trying to change the FROM header using sendmail. During the time I receive email from a server, I need to get FROM address as gsesvnadmin@gsesvn.corp.abc.com

Sendmail.mc

MASQUERADE_AS(gsesvnadmin@gsesvn.corp.abc.com)dnl
FEATURE(masquerade_envelope)dnl
FEATURE(masquerade_entire_domain)dnl
MASQUERADE_DOMAIN(gsesvn.corp.abc.com)dnl

My expectation:

FROM: gsesvnadmin@gsesvn.corp.abc.com , but what it returns is, gsesvnadmin@prod007.corp.abc.com
How to suppress the hostname, and get the actual output that what am passing?

Prod007 is the hostname of that server.