Version: 1.9.10 (using KDE 3.5.10) OS: Linux Installed from: Slackware Packages I have configured Kmail to get mail from mail.home.nl and mail.verhoeven272.nl. It fetches mail there in interval mode without problems. When I press "Manual mail check" I get the error 'unknown server' for each of them. But when the interval expires, the mail is fetched automatically. Sending (on authenticated server) is errorfree. After some time, I can press manual mail check again, without the error report. Kmail runs reliably. But sometimes this strange quirk happens. Only for your information.
Thanks for your bugreport. This is already fixed in kmail 1.11.0 (kde 4.2.0). Marking this bug as INVALID (NOTABUG) because it was already solved.
In fact, this is a duplicate of bug 171230