Messages for iOS 10 and MacOS Sierra 10.12 doesn’t do all they could to protect users information when they preview a link mentioned in a conversation. Only the IM services server exposes its IP address during that process. Messages makes that request from each device operated by the recipient, which enables actors to conduct some reconnaissance on their target. A recipient doesnt need to click on a link for iMessage to make that request, something which attackers can exploit to their advantage.”]
Source: https://grahamcluley.com/apple-messages-exposing-privacy-previews-link/