Hi, The dbox page says: "Each message has a 128 bit globally unique identifier (GUID)" I guess this is what guid_128_generate() generates. Is this believed to be really globally unique? As far as I can tell, in the current architecture they are -given there are enough time precision-, because all dovecot daemons are single threaded, so they have concurrency but doesn't have parallelism (they are not multi threaded). I would like to list all of the messages, with this GUID as the unique identifier, so a collision would be fatal here...