Google blocks anything over 25mb - When I tried attaching a report.zip using google it told me it was too big and then asked me if I wanted to use google drive, and then I just clicked the prompts and it took care of everything from uploading the file to sharing it.
Suggest you try that, it is seamless when sent that way for both you and the receiver.
I guess it depends on what your problem actually is. Usually, you would probably want to send them the save game(s) that manifest a problem or bug, and leave the others out. If all your save games have that problem, you would want to send just one(or a few) of them, not all.