SOGo supports password algoritm like {algoritm}password.

In my LDAP passwords looks like:
{plain}123456

So I put to SOGo configuration:
SOGoUserSources = (
{
type = ldap;
...
userPasswordAlgorithm = plain;
passwordPolicy = NO;
prependPasswordScheme = YES;
}
);

So when I put password 123456 in authorization form I cannot login.

But when I put {plain}123456 I can login.

When changing passwords by SOGo in ldap I have {plain}123456 (this is correct), so why I cannot login ?