Past SAR's to Lost Participant now found

I think I remember that, regarding disclosures, it is the Participant's responsibility to keep their address up to date.  

If a lost participant is found, I think I remember that we do not have to send past notices, SAR, 404, etc.  But I cannot remember where I got this idea.

What do you all think?  Do we need to send past notices when we find someone?

Much as we would all like to believe that participants should be responsible, the DOL's current position is that it is the plan sponsor's responsibility to keep track of the participant. 

I think this requires fiduciary judgment.  If you a find a participant or a participant finds you, at a minimum give that participant the notices that are currently relevant.  I don't see a need to send the participant a 20-year old SAR, and I can't imagine the DOL or a court would ding you for that - assuming the plan acted in accordance with ERISA's fiduciary duties all those years.  Of course, written requests would be a different matter.  If you want to dot all your i's and cross all your t's and mitigate all risk, give the participant everything.