Similar questions to mine have been asked before and answered. But I need some basic understanding of the function of 'kwallet'. I was under the impression that 'kwallet' , once opened, allows all programs that require passwords and have the password stored in 'kwallet' , to access 'kwallet' for their password if needed without having to prompt again for the password for 'kwallet'. At least such a procedure would make sense to me.
Here is my problem:
I'm running opensuse leap 42.1 with KDE Plasma 5.5.5. When I log in I'm prompted for the 'kwallet' password because my WLAN needs its password stored there. So 'kwallet' is now open. Later I'm stating 'kmail' and again I'm prompted for the 'kwallet' password although it is open. What have I done wrong and is it possible to configure my system in such a way that I'm only once being prompted for the 'kwallet' password for the whole session?
Thanks for any advice!

The likely reason for your problem is that you use kmail 4.14, which is still KDE4 based and uses the KDE4 wallet, while the desktop/plasma-nm uses the KF5 wallet. So when you start kmail, the (KDE4) wallet is actually *not* open.

kmail5 (being the port to KF5) does use the KF5 wallet like the desktop/plasma-nm, so switching to that may be an option for you (it is included in Leap 42.1 in version 15.12.3, just not installed/used by default).

Another way to get rid of having to enter a password is to set an empty password for your wallet (in kwalletmanager for the KDE4 wallet, or in kwalletmanager5 for the KF5 wallet).
This of course means that the passwords are stored unencrypted, only obfuscated. So if anybody could access your kwallet file, he also can extract your passwords.
You have to decide yourself if you prefer the security risk, or rather the convenience.
Personally, this is how I am using kwallet here since 13 years...

Thanks, Wolfi323, for your reply. You were spot on. Changing to 'kmail5' did the job. I just wonder why this hasn't been part of an update. Without your help it wouldn't have occured to me that this is the problem.

gm40 wrote:I just wonder why this hasn't been part of an update.

When openSUSE Leap 42.1 was released, kmail5 was still quite new and problems were to be expected.
So it had been decided to stick with kdepim4, and only offer kdepim5 as option.

And to avoid a misunderstanding, 42.1 shipped with kdepim5 15.08 (which was the first KF5 based version), there has been official updates later on up to 15.12.3.
But you won't be switched to kdepim5 automatically, not even in 42.2 (which does install kdepim5 by default though).
That is to avoid surprises.

Although 42.3 will likely not have kdepim4/kmail4 at all any more, so even upgrades will then install kdepim5 and remove kdepim4.
After all, kdepim4 is unmaintained upstream since July 2015, the only currently maintained/developed version is kdepim5...