As part of your build steps, create a property file to send downstream and copy the file to the folder of the next job. Use the Inject environment variables plugin in the second job to import the file.
In Job 1's build steps you could do something like
echo Recipients_Notified=%BUILD_USER_EMAIL%, %Distribution_List% cc:%[email protected]% > email.properties
echo Subject_Line=%APP% Pipeline>> email.properties
echo Line_1=information you want sent from first build to be in the communication>> email.properties
copy email.properties "..\%APP% Job Name\email.properties"
In Job 2 you can add to that file or overwrite it with a different message once the build is successful. Importing the file a second time will overwrite the parameters imported the first time.
