I'm working much with the SetTimeStamp request. (Archiving App. !!)

Now I would like to have a way to completely reset the timestamp (as if
I never had set it - like a new Mailbox). When I do a GetTimestamp on a
new Mailbox I get back 000000000T00000000Z (or similar).
I have found out that the earliest time I can set is 19700101T000001Z
any timestamp before is ignored and not set although the Status of the
request came back as OK.
So, What value do I have to send to completely reset the timestamp
(restore the 'virgin' state) ?

Thanks in advance