how to stop mail compressing images

Trying unsuccessfully to send a hi res image to a windows recipient. They can't open an eps. Saved as a pdf but that looked pixelated.

If I save as a jpeg it compresses the file even more when mailed.

Saw an earlier discussion (now locked) where solution was to select large from a drop down menu but I don't know where that drop down menu is, whether on mail or photoshop app, can't find it?

What am I doing wrong?