If the user has is trying to send a signed e-mail message with OCSP turned on and OCSP validation fails, the user sees the generic "Sending of message failed. Please make sure your account settings are set up correctly." The error message should say something about how OCSP failed and alert the user what really went wrong.
S/MIME bugs are automatically nsbeta1 candidates. (this is a bulk update - there may be some adjustment of the list).
*** This bug has been marked as a duplicate of 131087 ***