How about changing your password prior to doing the backup, and then change them back once it is done? There would be a window of opportunity, but you can check the gmail access log if that bothers you.

The idea of this program is great, it looks like it is a well developed tool, especially for migrating from a regular Gmail account to a Your Domain Gmail Account.

I would really love to use this tool, but I am afraid I just cannot trust it or its developers. I appreciate that you are developing and releasing this tool as freeware, but there is too much privacy at stake to trust your software. Many users of Gmail will have used their accounts for many financial transactions and private correspondence. We cannot just blindly hand over the keys to our account to you. We have to assume that you may be collecting usernames and passwords for these accounts in a type of phishing scam.

Were we cannot see the source code of your software this is a perfectly reasonable to assume. It has already been discovered after decompiling another program that did the same job, that the developer was indeed sending collected user details to his own account. The program in question is called G-Archiver, read more here http://uneasysilence.com/archive/2008/03/13052/

If you want users to trust you and use your software, and you would like more donations and input into your project, then release the code. What do have to hide.