This is the Wiadomość grupowa icon for Windows 10. Here we go. Optimized for 32x32 px, these are the simplest icons in the line style. Downloadable formats are PNG and SVG, among others. Icons8 icon pack is unique in providing a huge number of icons designed by the same team of four designers who create the new icons every working day in the same style and with the same quality. Same cool as the Bat Face, huh.
The icon is a picture of group message. The icon is the shape of two rectangles. The rectangle in front of the other one looks like an envelope. The envelope looking rectangle is slightly lower and to the right of the rectangle behind it.