Email moderation is a great replacement for mail group restriction. Instead of maintaining access lists on your key mail groups, just enable moderation on them and distribute the responsibility for approving email flow.
When you deal with Dynamic groups, those with predefined cafeterias for manipulating membership, it becomes interesting when those groups become so big. For example, you can create a dynamic group for all people who has a specific country code or office location. Those groups are very good candidate for moderation I believe.
Sometimes, when you deal with dynamic groups in Exchange , you should moderate those groups specially if those groups represents all employees in specific country or office,etc.
The strange thing about Moderated dynamic groups is the fact that you cannot view the moderation info of a moderated group from the Exchange Admin console, you need to go to powershell to do that.
Also, many times, you want to give your IT teams, or business people, a documentation about moderation info in the organization. In my case, i have a script that generate an excel sheet with all moderated groups, along with the moderation info for each group and i publish them via email enabled SharePoint list.
Script Feature :
Generate CSV with option to email it, with info about all moderated groups and the following info :
You can download the script from here: Get-MailingGroupModeration