boxicons/svg/regular/bx-envelope-open.svg

<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24"><path d="m21.555 8.168-9-6a1 1 0 0 0-1.109 0l-9 6A1 1 0 0 0 2 9v11c0 1.103.897 2 2 2h16c1.103 0 2-.897 2-2V9c0-.334-.167-.646-.445-.832zM12 4.202 19.197 9 12 13.798 4.803 9 12 4.202zM4 20v-9.131l7.445 4.963a1 1 0 0 0 1.11 0L20 10.869 19.997 20H4z"/></svg>