Trying to send us a DxDiag or a proof of purchase? If your DxDiag file is larger than 100MB, double-check that it’s saved as a .txt file. If it’s a text file or an image that’s bigger than 100MB, try compressing it:
On Mac, you can right-click the image and select Compress to create a zip file.
This will make a smaller zip file that you should be able to attach to your case.