I agree with you, D.W., if I understand correctly what you're saying between the lines. Some of the laws regarding handling classified info are probably foolish and obsolete in the email age, and certain when using the .gov email addresses they are sent, to my knowledge, through servers that could be hacked just like any other. In principle, though, they are at least supposed to be kept on machines in secured areas, which is something, and if the servers using that domain are somehow monitored with extra security maybe that makes them safer in a legitimate sense. This last point is the thing I really don't know.
However in the case of Hillary that good question is somewhat beside the point because when looking at this case we're talking about a machine kept by civilians in an unsecured area, which is over and above the issue of the method of transmitting those emails. Even Blumenthal's PC was hacked, which contained copies of many of those emails, meaning his machine was also a security risk.
In terms of how classification through email is supposed to work, there are various statements out there by government intelligence people that address that. There are mixed messages on that score, some of whom say the classification system is broken anyhow, and others who say that even a novice in government would know not to do what Hillary did. It's pretty easy to cherry pick answers to suit any position one may have on the subject.
