I have created rules to sort the mail.
If mail is unread in the inbox, the rules are executed correctly. However, if the mail has been marked as read on the SmartPhone, for example, the rule is no longer applied.
As the mail “has already been read on the Server by another device”, then eM Client won’t automatically move it with a rule when it reads your remote Inbox, “due to the status has already changed on the server from unread to read”.
The only way then is to either “manually apply the Rule” or “manually move the email to the folder” as @Gary advised in that other thread link.
To me, this explanation seems more like a technical reasoning as to how it is implemented, not a reason for why it is implemented that way. No matter what is happening on the server, message being marked as read or unread, the filter should work according to its definition (nothing defined there regarding read/unread messages on the server). Implementing it might be more difficult because of the rules being applied (partially?) on the server side, but that doesn’t mean this couldn’t be done on the email client side as well. The client knows the filter rule, since it was setup in the client, and it knows which incoming mails are new to its inbox, thus need to be checked against the filter rules and handled correspondingly. I see no technical reason as to why this shouldn’t be possible.