[Mailman-Users] Making a Case for Upgrading MailMan from 2.1.17

[Dave Nathanson]

I'd like some help in making a case to convince my hosting company to upgrade from Mailman 2.1.17. 

I run several email lists for clubs, these are discussion lists that get up to 20 messages per day, and include up to 150 members. Replies are directed back to the list. 

My primary issue with MM 2.1.17 is about list messages from members who don't have their human names configured into their email clients, resulting in a list message from an unknown. It is just from "via listname <listname at example.com>" 
Since I'm still stuck on 2.1.17. I don't know what I am missing in the newer versions. I just know that it's been over 2 years since 2.1.17 which has an annoying omission due the the whole DEMARC thing. 

What are the advantages of upgrading beyond 2.1.17? 
How best to make a good case to convince them to upgrade their MailMan?
What version should I ask for? 

Thanks! 
 Dave Nathanson
 Mac Medix