If you get an error message in your mail client that cannot verify the identity of the server (certificate):

In the mail program, go to the mail account settings and change your incoming (POP/IMAP) and outgoing (SMTP)** servers to

mail.blueboard.cz

You probably had something like mail.vasedomena.xx in there before. Due to the newly installed certificate on our side and the tightening of security policy especially for Apple mobile devices, this old setting is no longer valid.