I can’t because they are not really stored anywhere that I know of, the description of whisper says it’s strictly real time push to a single individual. As far as I know, messages between us are stored just between us…but I really don’t know where…there’s no messaging database. I don’t believe it’s in the browser cache and I have no access to it. There apparently was a security issue, but i think it was plugged with the last ever update made.
Here is the discussion, if it makes any sense to you. Personally,|I would completely disable private messaging, if there was a way for users to communicate their e-mails for anyone they wanted to chat to …e.g. selling something, buying something. I gathered from reading the discussion they whisper uses the writers free pusher plan…and my experience has been pusher free is pretty poor and I will bet that’s why we’ve been getting lots of problems with it.
https://discuss.flarum.org/d/28256-whisper-encryption-less-private-messaging/68
I have had my thinking cap on for a while about how members can exchange e-mails in some way that’s secure, without disclosing them to spammers….I had an idea which might have worked, using spamgourmet but that’s now shut….I will think of something.