As sure as a newbie using summer to improve his skills can be! Thanks for considering the issue.
I think RoundCube is using IMAP here. The new attachment (9.8 KB) includes an n=36 series. It reproduces every 5 minutes. That is mainly why I’m guessing is Discourse-related. I’m not able yet to understand when n is equal to the number of messages in premise’s account inbox.
Thanks!