Help with Custom Exchange Role for Managing Distribution Lists and Mail Contacts

I'm trying to create a custom Exchange role for a single user that allows them to:

  • Manage existing Distribution Lists
  • Create new Distribution Lists
  • Add\Remove Mail Contacts for external users

I attempted to create this custom role via PowerShell, but I can't seem to get it working properly. Either the user has too many permissions (like managing all mailboxes) or no access at all.

Has anyone successfully created a custom role for this scenario? Any guidance or working solutions would be greatly appreciated!