These columns are tracking columns that are used for email marketing campaigns.
clickts – is the date/time that someone clicked a link
clickip – is the IP address of the person that clicked the link
viewts – is the date/time that someone viewed the message
viewip – is the IP address of the person that viewed the message.
These columns are overwritten anytime a list is used in a campaign and stores the last time a user viewed a message or clicked a link.