I just tried to send 1.6GB worth of jpegs in a zipped file. I got an error -1 (tried 3 times). It seems like it was during the virus checking. I sent the same jpeg files without zipping and it worked. Is this normal?
I'm not sure; it should work. It's possible that the virus-scanning is taking a long time on multiple JPEG files, and is eventually timing out on our server. By sending them individually, you are not hitting that time-out.
How many files are there in the 1.6GB zip file?