Is there a way to have Mac Mail compress images to PNG rather than JPEG by default? I've noticed that a high resolution JPEG source image looks better when compressed to a low resolution PNG than a low resolution JPEG.

Screenshots can be saved as PNGs with this:

defaults write com.apple.screencapture type png

I'm looking for something analogous to this.

  • 1
    My mail just adds the image I present it, compression is optional. Just attach a PNG if you want a PNG Jul 21, 2015 at 20:57
  • Thanks. I know Mac Mail will keep a PNG a PNG, but I'm trying to save a step in converting a JPEG to a PNG. I.e. my camera takes JPEGs, and I want to send out reduced resolution PNGs. I'd rather not open the photo in Preview and reduce/convert manually. Jul 21, 2015 at 22:59
  • 1
    It is not the task of Mail to handle this. Have you looked at Automator? Automator can convert, compress images and setup an email message (using Apple Mail) Jul 22, 2015 at 4:48
  • That's helpful. Thanks. I will look at Automator. Jul 23, 2015 at 6:25


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