diff --git a/lib/install.sh b/lib/install.sh
index e00d7f0..cb778ca 100755
--- a/lib/install.sh
+++ b/lib/install.sh
@@ -226,7 +226,6 @@ function check_credential {
     check_yaml_defined_value /etc/miaou/defaults.yaml 'credential.username' &&
         check_yaml_defined_value /etc/miaou/defaults.yaml 'credential.shadow' &&
         check_yaml_defined_value /etc/miaou/defaults.yaml 'credential.email'
-
 }
 
 function check_target() {
@@ -260,7 +259,7 @@ function miaou_configfiles() {
     if [[ ! -f /etc/miaou/defaults.yaml ]]; then
         echo -n "building /etc/miaou/defaults.yaml for the first time..."
         shadow_passwd=$(sudo grep "$CURRENT_USER" /etc/shadow | cut -d ':' -f2)
-        env current_user="$CURRENT_USER" shadow_passwd="$shadow_passwd" tera -e --env-key env --env-only -t "$MIAOU_BASEDIR/templates/etc/defaults.yaml.j2" -o /etc/miaou/defaults.yaml >/dev/null
+        env current_user="$CURRENT_USER" shadow_passwd="$shadow_passwd" valid_email="$valid_email" tera -e --env-key env --env-only -t "$MIAOU_BASEDIR/templates/etc/defaults.yaml.j2" -o /etc/miaou/defaults.yaml >/dev/null
         yq ".target=\"$TARGET\"" /etc/miaou/defaults.yaml -i
         PREFIX="" echoinfo OK
     fi
@@ -339,8 +338,7 @@ EOF
 }
 
 function extra_dev_desktop {
-    # detect if DEV
-    # detect if DESKTOP
+    # FIXME: detect if DEV && DESKTOP_USAGE to install spicy-client and other desktop tools
     :
 }
 
@@ -363,15 +361,13 @@ EOF
     fi
 }
 
-function ask_for_credential {
-    local PREFIX="ask:credential"
-    if ! check_credential 2>/dev/null; then
-        echo "further details required, please replace any <TO BE DEFINED> by a proper value ...press any key to open editor"
-        read -rn1
-        editor /etc/miaou/defaults.yaml
-    fi
-    check_credential
-    echo "successfully checked!"
+function ask_for_email {
+    local PREFIX="install:ask_for_email"
+    valid_email=$(auto_detect_email)
+    while ! is_email_valid "$valid_email"; do
+        echo -n "mandatory email: "
+        read -rei "$valid_email" valid_email
+    done
 }
 
 function preload_bookworm_image {
@@ -393,7 +389,15 @@ function is_email_valid {
 }
 
 function auto_detect_email {
-    :
+    found_email=""
+    if [[ -f $HOME/.ssh/authorized_keys ]]; then
+        while IFS= read -r line; do
+            found_email="$line"
+            is_email_valid "$found_email" && break
+        done < <(cut -d ' ' -f3 <"$HOME/.ssh/authorized_keys")
+    fi
+
+    builtin echo "$found_email"
 }
 
 ### MAIN
@@ -423,8 +427,11 @@ else
     TARGET=${1:-}
     CURRENT_USER=$(id -un)
 
-    sudo_required
+    check_normal_user
     check_target
+    ask_for_email
+
+    sudo_required
     install_miaou_bash
     install_mandatory_commands
     prepare_toolbox
@@ -435,7 +442,6 @@ else
     miaou_resolver
     miaou_evalfrombashrc
     miaou_configfiles
-    ask_for_credential
     opt_link
     extra_dev_desktop
 
diff --git a/templates/etc/defaults.yaml.j2 b/templates/etc/defaults.yaml.j2
index 8bf1ee9..dfac725 100644
--- a/templates/etc/defaults.yaml.j2
+++ b/templates/etc/defaults.yaml.j2
@@ -5,4 +5,4 @@ containers:
 credential:
   username: {{env.current_user}}
   shadow: {{env.shadow_passwd}}
-  email: TO BE DEFINED # example user@domain.tld
+  email: {{env.valid_email}}