Threema-Android-mirror/app/src/main/res/drawable/ic_send_outline.xml

<vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:width="48dp"
    android:height="48dp"
    android:viewportWidth="24"
    android:viewportHeight="24">
  <path
      android:fillColor="#FF000000"
      android:pathData="M4.01,6.03l7.51,3.22 -7.52,-1 0.01,-2.22m7.5,8.72L4,17.97v-2.22l7.51,-1M2.01,3L2,10l15,2 -15,2 0.01,7L23,12 2.01,3z"/>
</vector>