Following up my posting of the relevant section of the press conference transcript, Business Insider has posted the full official statement as well. Here are the relevant sections related to email security.
Was classified material sent or received by Secretary Clinton on this email
No. A separate, closed system was used by the Department for the sole purpose of
handling classified communications which was designed to prevent such
information from being transmitted anywhere other than within that system,
including to outside email accounts.
How did Secretary Clinton receive and consume classified information?
The Secretary’s office is located in a secure area. Classified information was
viewed in hard copy by the Secretary while in the office. While on travel, the
Department had rigorous protocols for her and traveling staff to receive and
transmit information of all types.
Where was the server for her email located?
The server for her email was physically located on her property, which is protected
by U.S. Secret Service.
What level of encryption was employed? Who was the service provider, etc?
The security and integrity of her family’s electronic communications was taken
seriously from the onset when it was first set up for President Clinton’s team.
While the curiosity in the specifics of this set up is understandable, given what
people with ill-intentions can do with such information in this day and age, there
are concerns about broadcasting specific technical details about past and current
practices. However, suffice it to say, robust protections were put in place and
additional upgrades and techniques employed over time as they became available,
including consulting and employing third party experts.
Was the server ever hacked?
No, there is no evidence there was ever a breach.
Was there ever an unauthorized intrusion into her email or did anyone else
have access to it?
What was done after her email was exposed in February 2013 after the hacker
known as “Guccifer” hacked Sid Blumenthal’s account?
While this was not a breach of Secretary Clinton’s account, because her email
address was exposed, steps were taken at that time to ensure the security and
integrity of her electronic communications.