I'm not sure what this means or if I should be worried but it's weird.
Quick example of OEM
- CPUs without a box and just in a plastic case. No manual or anything.
- HDD without a box normally in a static guarded bag.
- CDs/DVDs usually just in a case/sleeve with the not for retail sticker on it. Windows OEM still come in a nice case, but say you can't resell it.
Usually just bulk items that aren't going to be used for reselling. Basically what that email is telling you, is that you cannot have an OEM item and say it is New. New on Amazon refers to sealed with a box and manual which is normally what OEM items do not come with.