How to change source SMTP IP address in sendmail
April 24, 2008 by Mohammed
Follow the steps below, if you want to change the source SMTP ip address in sendmail.
1) change the line below in sendmail.cf
#O ClientPortOptions=Family=inet, Address=x.x.x.x
to
O ClientPortOptions=Family=inet, Address=
3) restart sendmail
Send a test mail and check its header. The source IP address should have changed
REFERENCES
http://mohammednv.wordpress.com/2008/04/24/how-to-change-source-smtp-ip-address-in-sendmail/