I can't replicate this. I use the same versions with no problems.

I configured some env variables instead of typing each time the list of recipients.
So in the main jenkins configuration there is a variable MAILING_LIST_JAVA and in each job i type $MAILING_LIST_JAVA in recipient form, but when I re-open a previously saved configuration I always see $DEFAULT_RECIPIENTS

I also use environment variables in my configuration and have no issues. Are you sure you are running 2.24.1? Did you restart Jenkins after upgrading?

Yes, i allways use to check the checkbox "restart jenkins after plugin installation".
I don't see error in logs on restart.

I just tried this again to make sure, and I am unable to reproduce the issue.

The environment where i'm having this issue is a Red Hat Enterprise Linux Server release 6.2 (Santiago)
Tocmat 7.
Java(TM) SE Runtime Environment (build 1.6.0_30-b12)
Java HotSpot(TM) 64-Bit Server VM (build 20.5-b03, mixed mode)

Unfortunately I don't know how to give you more info..
Could I set a different log level for this plugin?

Thanks for your investigation.

No, there isn't a higher level of logging for the plugin. Can you try looking at the HTTP traffic in your browser when you submit and send the fields that are being sent to the server?

Looks like your Jenkins version is pretty old. Can you try upgrading to the most recent LTS (1.466.x) and see if you still have the issue. The testing for the plugin is always done with the latest LTS.