diff --git a/omnisend/includes/Internal/class-connection.php b/omnisend/includes/Internal/class-connection.php
index ff20016..b37d792 100644
--- a/omnisend/includes/Internal/class-connection.php
+++ b/omnisend/includes/Internal/class-connection.php
@@ -38,6 +38,11 @@ public static function display(): void {
 			}
 		}
 
+		if ( ! $connected ) {
+			require_once __DIR__ . '/../../view/connection-form.html';
+			return;
+		}
+
 		require_once __DIR__ . '/../../view/connection-success.html';
 	}
 
diff --git a/omnisend/includes/Internal/class-utils.php b/omnisend/includes/Internal/class-utils.php
index 591c883..6de2f94 100644
--- a/omnisend/includes/Internal/class-utils.php
+++ b/omnisend/includes/Internal/class-utils.php
@@ -19,7 +19,7 @@ class Utils {
 	 * @return bool
 	 */
 	public static function is_valid_custom_property_name( $name ): bool {
-		return preg_match( '/^[a-zA-Z0-9_]{1,128}$/', $name );
+		return is_string( $name ) && preg_match( '/^[a-zA-Z0-9_]{1,128}$/', $name );
 	}
 
 	/**
@@ -30,7 +30,7 @@ public static function is_valid_custom_property_name( $name ): bool {
 	 * @return bool
 	 */
 	public static function is_valid_tag( $tag ): bool {
-		return preg_match( '/^[a-zA-Z0-9_\- ]{1,128}$/', $tag );
+		return is_string( $tag ) && preg_match( '/^[a-zA-Z0-9_\- ]{1,128}$/', $tag );
 	}
 
 	/**
diff --git a/omnisend/includes/Public/V1/class-contact.php b/omnisend/includes/Public/V1/class-contact.php
index 3a6c0a2..bb69b7e 100644
--- a/omnisend/includes/Public/V1/class-contact.php
+++ b/omnisend/includes/Public/V1/class-contact.php
@@ -73,7 +73,7 @@ public function validate(): WP_Error {
 			}
 		}
 
-		if ( $this->email != null && ! is_email( $this->email ) && $error['email'] == null ) {
+		if ( $this->email != null && ! is_email( $this->email ) ) {
 			$error->add( 'email', 'Not a email.' );
 		}
 
@@ -81,10 +81,6 @@ public function validate(): WP_Error {
 			$error->add( 'send_welcome_email', 'Not a valid boolean.' );
 		}
 
-		if ( $this->phone != null && ! is_numeric( $this->phone ) && $error['phone'] == null ) {
-			$error->add( 'phone', 'Not a valid phone number.' );
-		}
-
 		if ( $this->phone == null && $this->email == null ) {
 			$error->add( 'identifier', 'Phone or email must be set.' );
 		}
@@ -99,9 +95,9 @@ public function validate(): WP_Error {
 			}
 		}
 
-		foreach ( $this->custom_properties as $custom_property ) {
-			if ( ! Utils::is_valid_custom_property_name( $custom_property ) ) {
-				$error->add( 'custom_properties', 'Custom property "' . $custom_property . '" is not valid. Please cleanup it before setting it.' );
+		foreach ( $this->custom_properties as $custom_property_name => $custom_property_value ) {
+			if ( ! Utils::is_valid_custom_property_name( $custom_property_name ) ) {
+				$error->add( 'custom_properties', 'Custom property "' . $custom_property_name . '" is not valid. Please cleanup it before setting it.' );
 			}
 		}