If you attempted to use SSL to connect to a server that speaks
STARTTLS, you should get an SSL protocol error. Instead, you
were likely to get an "Unrecognized Certificate" error that shows
you an unrelated certificate chain and asks you to accept it or
reject it. Neither action would work because the actual problem
had nothing to do with certificates. The unrelated certificate
chain that popped up had been statically stored when validating
a prior connection to a different server.
With this patch, certificate chains are no longer stored statically
when validating server connections.
Issue 5886 is an example of a user experiencing this problem.
The commit that introduced those notifications also introduced a rather
... interesting design pattern: The CertificateValidationException
notified the user of its pure existance - it's no longer a 'message'
only, but defines policy. As this is more than unusual, replace this
pattern by the MessagingController treating
CertificateValidationException specially when accessing remote folders.
Also make clear which account failed when constructing the notification.
With this fix, a CertPathValidatorException or CertificateException will
create a "Certificate error: Check your server settings" notification
in the status bar. When the user clicks on the notification, they are
taken to the appropriate server settings screen where they can review their
settings and can accept a different server certificate.