Added Yahoo! recognition

app/src/main/java/eu/faircode/email/MessageHelper.java

@@ -1728,6 +1728,10 @@ public class MessageHelper {
         if (!TextUtils.isEmpty(outlook))
             return "outlook";
 
+        String yahoo = imessage.getHeader("X-Sonic-MF", null);
+        if (!TextUtils.isEmpty(yahoo))
+            return "yahoo";
+
         return null;
     }
 

app/src/main/res/drawable/infra_yahoo.xml

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="300dp"
+    android:height="300dp"
+    android:viewportWidth="300"
+    android:viewportHeight="300">
+  <path
+      android:pathData="m290.575,94.837c-5.201,0.514 -26.852,5.364 -34.129,6.924 -7.792,2.074 -78.984,57.075 -83.661,70.581 -1.037,4.674 -1.556,11.866 -1.556,18.624l-0.522,10.916c0,7.788 2.164,20.349 3.2,27.102 4.681,1.043 38.555,0.132 44.788,1.168l-0.767,13.97c-6.091,-0.444 -49.106,-0.34 -73.68,-0.34 -12.475,0 -52.576,1.375 -64.897,1.004l2.329,-13.285c6.756,-0.524 34.729,1.207 40.879,-5.284 3.055,-3.221 2.081,-6.672 2.081,-25.376v-8.832c0,-4.158 0,-11.956 -1.043,-19.233 -2.597,-7.796 -65.301,-86.09 -81.409,-98.558 -4.681,-1.557 -33.99,-4.489 -41.264,-6.051l-0.362,-11.968c3.629,-1.819 36.221,0.442 67.849,-0.728 20.787,-0.768 68.215,0 74.067,0.697l-1.499,10.547c-6.234,1.561 -36.266,2.138 -44.062,4.215 20.268,30.139 52.312,68.94 62.707,84.011 5.719,-8.313 55.954,-42.874 57.512,-54.825 -7.797,-1.565 -33.607,-5.279 -37.766,-5.279l-2.469,-13.607c7.075,-1.107 44.278,0 62.774,0 15.962,0 50.07,0 59.762,0.794l-8.863,12.813"
+      android:fillColor="#592c71"/>
+</vector>

app/src/main/res/values/strings.xml

@@ -1823,6 +1823,7 @@
 
     <string name="infra_gmail" translatable="false">Gmail</string>
     <string name="infra_outlook" translatable="false">Outlook/Office 365</string>
+    <string name="infra_yahoo" translatable="false">Yahoo!</string>
 
     <string-array name="pollIntervalNames">
         <item>Always</item>