diff --git a/gdpr-content-blocker/gdpr-content-blocker.php b/gdpr-content-blocker/gdpr-content-blocker.php
index 8d7dcd6..9c2a8db 100644
--- a/gdpr-content-blocker/gdpr-content-blocker.php
+++ b/gdpr-content-blocker/gdpr-content-blocker.php
@@ -3,7 +3,7 @@
  * Plugin Name: GDPR Content Blocker
  * Plugin URI:  https://lucas-orth.de/wp-plugins/gdpr-content-blocker/
  * Description: DSGVO-konformer Consent-Blocker für externe iframes. Lädt Drittinhalte erst nach aktiver Einwilligung.
- * Version:     1.5.3
+ * Version:     1.5.4
  * Author:      Lucas Orth
  * Author URI:  https://lucas-orth.de
  * Text Domain: gdpr-content-blocker
@@ -15,7 +15,7 @@
 
 defined( 'ABSPATH' ) || exit;
 
-define( 'CB_VERSION',  '1.5.3' );
+define( 'CB_VERSION',  '1.5.4' );
 define( 'CB_FILE',     __FILE__ );
 define( 'CB_DIR',      plugin_dir_path( __FILE__ ) );
 define( 'CB_URL',      plugin_dir_url( __FILE__ ) );
diff --git a/gdpr-content-blocker/includes/class-license.php b/gdpr-content-blocker/includes/class-license.php
index 8e40da8..bbc12f7 100644
--- a/gdpr-content-blocker/includes/class-license.php
+++ b/gdpr-content-blocker/includes/class-license.php
@@ -371,9 +371,18 @@ class CB_License {
 		</tbody></table>
 
 		<?php if ( $status === 'limit' ) : ?>
-			<!-- Not enough seats to activate this site: offer an upgrade. -->
+			<?php
+			// Upgrade = open a pre-addressed e-mail with empty fields to fill in.
+			$mail_subject = rawurlencode( __( 'Lizenzupgrade', 'gdpr-content-blocker' ) );
+			$mail_body    = rawurlencode(
+				__( 'Lizenzkey:', 'gdpr-content-blocker' ) . " \r\n"
+				. __( 'Bestellmail:', 'gdpr-content-blocker' ) . ' '
+			);
+			$mailto = 'mailto:info@lucas-orth.de?subject=' . $mail_subject . '&body=' . $mail_body;
+			?>
+			<!-- Not enough seats to activate this site: offer an upgrade by e-mail. -->
 			<p style="margin:8px 0 16px;">
-				<a href="https://lucas-orth.de/wp-plugins/gdpr-content-blocker/" target="_blank" rel="noopener noreferrer" class="button button-primary">
+				<a href="<?php echo esc_url( $mailto ); ?>" class="button button-primary">
 					<?php esc_html_e( 'Lizenz upgraden', 'gdpr-content-blocker' ); ?>
 				</a>
 				<span class="description" style="margin-left:8px;">
diff --git a/gdpr-content-blocker/languages/gdpr-content-blocker-en_US.mo b/gdpr-content-blocker/languages/gdpr-content-blocker-en_US.mo
index a789998..6bfac11 100644
Binary files a/gdpr-content-blocker/languages/gdpr-content-blocker-en_US.mo and b/gdpr-content-blocker/languages/gdpr-content-blocker-en_US.mo differ
diff --git a/gdpr-content-blocker/languages/gdpr-content-blocker-en_US.po b/gdpr-content-blocker/languages/gdpr-content-blocker-en_US.po
index 468fe60..a8be517 100644
--- a/gdpr-content-blocker/languages/gdpr-content-blocker-en_US.po
+++ b/gdpr-content-blocker/languages/gdpr-content-blocker-en_US.po
@@ -57,6 +57,15 @@ msgstr "Status"
 msgid "Domain"
 msgstr "Domain"
 
+msgid "Lizenzupgrade"
+msgstr "License upgrade"
+
+msgid "Lizenzkey:"
+msgstr "License key:"
+
+msgid "Bestellmail:"
+msgstr "Order e-mail:"
+
 msgid "Lizenz upgraden"
 msgstr "Upgrade license"
 
diff --git a/hilfsdaten/strings.txt b/hilfsdaten/strings.txt
index dda53ea..19e9246 100644
--- a/hilfsdaten/strings.txt
+++ b/hilfsdaten/strings.txt
@@ -1,4 +1,4 @@
-# 138 unique strings
+# 141 unique strings
 MSGID	Ungültige Antwort vom Lizenzserver.
 MSGID	Keine Berechtigung.
 MSGID	Bitte einen Lizenzschlüssel eingeben.
@@ -16,6 +16,9 @@ MSGID	Alle Plätze belegt
 MSGID	Nicht aktiviert
 MSGID	Status
 MSGID	Domain
+MSGID	Lizenzupgrade
+MSGID	Lizenzkey:
+MSGID	Bestellmail:
 MSGID	Lizenz upgraden
 MSGID	Schalten Sie weitere Domains frei, um diese Seite zusätzlich zu aktivieren – oder geben Sie unten eine bestehende Domain frei.
 MSGID	Belegte Domains
diff --git a/hilfsdaten/translations-en.json b/hilfsdaten/translations-en.json
index 3d03136..1b45d29 100644
--- a/hilfsdaten/translations-en.json
+++ b/hilfsdaten/translations-en.json
@@ -137,5 +137,8 @@
  "Textausrichtung": "Text alignment",
  "Mittig": "Centered",
  "Linksbündig": "Left-aligned",
- "Rechtsbündig": "Right-aligned"
+ "Rechtsbündig": "Right-aligned",
+ "Lizenzupgrade": "License upgrade",
+ "Lizenzkey:": "License key:",
+ "Bestellmail:": "Order e-mail:"
 }
\ No newline at end of file