Kmail/Akonadi forgets pop3 mail server password

[Peter G.]

I have set up a pop3 mail server under Akonadi for each 
of the mail servers I use (my internet provider default, 
google and yahoo).

Roughly every third time I start Kmail, the yahoo pop3 
password needs to be reeintered. Why does it get 
forgotten by akonadi?

I reenter the password and the mail is checked, and then, 
a day or three later, the same thing again. This has been 
going on for weeks, perhaps months. I have ignored it, 
but it is frustrating. What is going on?