diff --git a/src/freedombone-installer b/src/freedombone-installer
index 3d98b58e9a74e3daa8c9e861a85552a884e9965f..b8b314afccc5105bceac2dd261bb03a42fb78cb8 100755
--- a/src/freedombone-installer
+++ b/src/freedombone-installer
@@ -151,6 +151,15 @@ function web_admin_background_color {
             sed -i "0,/ color:.*/s// color: ${fg_color};/" "$webfile"
         fi
     done
+
+    # change webmail theme
+    if [ -f "/var/www/${local_hostname}/htdocs/mail/config/config.php" ]; then
+        if [[ "$bg_color" == 'white' ]]; then
+            sed -i 's|theme_default.*|theme_default = 54;|g' "/var/www/${local_hostname}/htdocs/mail/config/config.php"
+        else
+            sed -i 's|theme_default.*|theme_default = 55;|g' "/var/www/${local_hostname}/htdocs/mail/config/config.php"
+        fi
+    fi
 }
 
 function web_admin_create_app_descriptions {
diff --git a/src/freedombone-utils-webadmin b/src/freedombone-utils-webadmin
index 3cfaf0ea8e8b44f8ba133fca9d01cd1615af55cc..6fd09f00aed8f5e9d82e83f7831adc4311700eba 100755
--- a/src/freedombone-utils-webadmin
+++ b/src/freedombone-utils-webadmin
@@ -52,6 +52,15 @@ function web_admin_background_color {
             sed -i "0,/ color:.*/s// color: ${fg_color};/" "$webfile"
         fi
     done
+
+    # change webmail theme
+    if [ -f "/var/www/${local_hostname}/htdocs/mail/config/config.php" ]; then
+        if [[ "$bg_color" == 'white' ]]; then
+            sed -i 's|theme_default.*|theme_default = 54;|g' "/var/www/${local_hostname}/htdocs/mail/config/config.php"
+        else
+            sed -i 's|theme_default.*|theme_default = 55;|g' "/var/www/${local_hostname}/htdocs/mail/config/config.php"
+        fi
+    fi
 }
 
 function web_admin_translate_text {