You can set the value of property bulkemailmid_tracking_optout_url via SAS Management Console --> Application management-->Configuration Manager-->SAS Application Infrastructure-->Digital marketing WebStudio SDMversion
to the desired valid html link (for ex. http://www.YourCompanyDomain.com/YourOptout.html) and rebuild and redeploy bess by running the config wizard.
Or else
make change to web.xml of tracking tier application (bess) and restart the mid-tier server.
Parameters redirect should be set to true and redirect_link should be set to appropriate value.
<servlet>
<servlet-name>optout</servlet-name>
<servlet-class>com.sas.email.servlets.OptOut</servlet-class>
<init-param>
<param-name>redirect</param-name>
<param-value>true</param-value>
</init-param>
<init-param>
<param-name>redirect_link</param-name>
<param-value> http://www.YourCompanyDomain.com/YourOptout.html</param-value>
</init-param>
<init-param>
<param-name>sync</param-name>
<param-value>true</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>