how can i logout usermin webmail ?there is no logout button .only switch user button is avaliable. please tell me how to add logout button .

That happens if you don’t use cookies and session-based authentication. If you use the HTTP authentication method, it doesn’t really have a way to “log out” a user, because it is a client-side thing. Any “log out” would be an illusion, so it only offers to change user. We don’t really recommend disabling session authentication without a really good reason (because it has some side effects, like this).

You can change that back to the default (session authentication) by browsing to (in Webmin, not Usermin) Webmin->Webmin->Usermin Configuration->Authentication, and setting “Authentication type” to “Enable session authentication”.