After the most recent plugin upgrade, we are unable to set the 'attach build log' option in our job configuration for the email-ext plugin. When you attempt to set the option to attach the build log and click save, it automatically reverts to 'Do Not attach Build logs'. The same behavior is seen when you try to set the option manually in the job xml as well. 

We have tested this issue on 2.492.2 and the 2.504.1, both having the problem

Downgrading to the previous version removes the issue