Using Built in newsletter mails problem

[color=#282828][font=arial, verdana, tahoma, sans-serif]when I use Built in newsletter mails and send the massage to users, in yahoo all images send as attachment in massage, and this cause bad quality of the massage, how can I avoid this[/font][/color]

[color=#282828][font=arial, verdana, tahoma, sans-serif]in other sites no attachment and the images saved in there site[/font][/color]

Try using JPG format instead of PNG.

most my photo is jpg and still be attached