How long data is kept
Messages are held only for as long as the review or reply needs them, plus a short period afterwards in case there is a follow-up question or a detail that needs checking twice. Once that window closes, the message is deleted.
Browsing information is kept in aggregate form — counts and patterns rather than individual visits. Aggregate records age out on a routine schedule. When a record is no longer useful it is deleted, or reduced to a form that no longer identifies anyone.