Scenario 1 :-
1. Import an email record into CRM Organization with the Created Date set to 5 days ago. For example current date is 10/30/2015, the email's Created On date would be 10/25/2015. Make sure that you "Set Regard" it to an contact record.
2. Post importing of the email record, open the Regarding contact record.
3. In the Social Pane, select the Activities tab.
4. Here you will see the date mentioned below the Email record is today i.e. the date when the record was imported to the organization and not the original email creation date.
Scenario 2 :-
1. Open an older email in the CRM organization under Sales -> Activities -> Emails -> All Emails
2. Set regard it with any Account, Contact, Lead record (Record that contains Social Pane on the form).
3.Once you set regard it, you will find that the date mentioned under the email is of Today instead of the older date.
Conclusion :- The Social Pane grabs the date when the record was modified or imported into the organization. It seems to be that the latest date of the record from the ActivityBasePointer table is rendered in the Social Pane and the Created On date is disregarded.