I get quite a few questions related to how secure and private data ran through the bulk geocoder will be kept. The quick answer is: Your data never really leaves your computer.
To explain, here’s what happens when you use batchgeocode.com. You paste your data into the field on the screen and validate it. You then select which field is which and select what map options you want and so on. So far so good, you haven’t even accessed the internet since you loaded the page (you can prove this on your own by unplugging your network cable after loading the page.)
The step of actually running the geocoder (and drawing the map) is the only step that actually interacts with the internet. However the only data that is actually transmitted is your address data, and it is not attached to any other information you may have included. So if someone out there happened to be interested enough to sniff the HTTP traffic, all they would see is a bunch of addresses, with no contextual information to place them in.
Now, say you choose to use the “Save Map to Web Page” feature… Well this will actually send your data to our server where they will be saved. So if you just can’t have your data go over the Internet, stay away from this option. “Download to Google Earth” sends the data as well, but it is never saved, just put into a KML which gets sent back to you and then destroyed.
A bit more on “Save Map to Web Page,” doing this will not automatically publish your information to the Internet so to speak. It will be available to anyone who knows the URL, but guessing the URL is impossible. So unless you choose to share it with anyone, it will remain a secret. You can use it in this way to create maps that are of personal interest to you, but no one
Hope that clears things up, if you have any questions please feel free to use the comments feature. If your one of those secretive types, you can even post anonymously.