How can we be able to check someone’s messages on spark without logging their accounts,
Thank you.
Explain your case with a bit more details. I guess you are asking to see someone’s chat history? Spark saves history (if it wasn’t disabled) locally on a computer of a user. On Windows this is in C:\Users\username\AppData\Roaming\Spark\user\username@servername\transcripts\ folder. Two xml files per contact. One is for quick history and another is storing whole history.
Another option is to use Monitoring Service plugin for Openfire server and archive messages. Then you can use the search option and this way find particular chats.