A recent visitor had this question:
Can you help me understand why distribution list sharing is so problematic? We have a user who shared out their dl to a group. When the members of the group attempted to open the distribution list, internal and external recipients, they would receive an error, 'invalid contact would you like to delete, fix'. I noticed if you click cancel, it drops you back to the dl and the icon before the contact changes.
When you select contacts as members of a distribution list, you're adding pointers to the contacts, not the actual contact. When a distribution list is shared, its looking for the contact in a specific path and the path changes when opened from another mailbox. The icon change from the Contact icon to a Rolodex style address card indicates the link to the contact is broken. You won't be able to use the Update button to update those contact's addresses.
While we're on the subject of distribution lists, when you update a DL, you need to delete the DL from the autocomplete list, otherwise the old version of the DL will be used. Delete it from the autocomplete cache then select the updated DL from your Address book.