iphoto question?

Hello all, i have question with respect to iPhoto. I sent via web 126 photos to Blacks to be developed and mailed back. This is my first time doing this. When the bundle came today many of the photos appeared cropped again. A crop the crop if you will. I called Blacks and they said that the files weren't all in 4 x 6 format. So i have been looking where I can do this but to no avail. I have a credit of some 25 pictures that i would like to get printed again but I do not want to make the same mistake....as it appears it was my fault.

So, how do I ensure I have a 4 x 6 when I send it to them.

Thanx

Rp

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