To be able to use eShuttle, the email accounts should do two things:
The email account should allow for the sending and receiving of large files. The actual size of the files can vary widely, but a good example would be a 15 minute file recorded on an Olympus handheld. This kind of file is about 2.7 MB in size.
The email account should allow sending and receiving files from a desktop email client. This is sometimes called POP access or POP3 access. Some free email services do not allow you to download files to a computer, and these services should be avoided. You can usually pay $15-$25 per year to allow email downloading.