Hello,
are a new user forum,
I have a problem with kmail:
a bit of time when that happens
kmail start, read messages marked as unread,
I had already read in the past.
I noticed that happens when I run kmail the morning, but
if during the day will end and then re-open Kmail,
works without problems.
In unsuccessful attempts, I tried to delete the file index of inbox folder (under .kde / share / apps / kmail / mail):

-. Inbox.index
-. Inbox.ids
-. Inbox.sorted

Is there anyone who can help me?
Thank you