We have found that there are many DL's in our organization that are still on old versions.
How to find DL versions:-
Log on to exchange 2010 management shell:
$collect = Get-DistributionGroup -ResultSize unlimited | select Name,samaccountname,exchangeversion
$collect | export-csv c:\exportDl.csv
Now you have two options to upgrade
1. upgrade all Lists at ones
Get-DistributionGroup -ResultSize unlimited | Set-DistributionGroup -forceupgrade
2. Do some of the lists to see how it goes like I have done only 250 to first check
Set-DistributionGroup "DLName" -forceupgrade
you can use notepad++ & you don't have to write any script, follow below screen shot.
step1: replace ^(.+)$ with "\1" (Regular expression should be selected at below)
step3: After replace it will look like below
Now enter these in Shell :)