Magento 1.9 Admin Event – Trigger After Invoice Save

First of all adminhtml_customer_save_after is correct event take a look in \app\code\core\Mage\Adminhtml\controllers\CustomerController.php.

customer_save_after it is a different event for frontend.

But your class definition is wrong. Try this

<events>
    <adminhtml_customer_save_after>
        <observers>
            <electronicsstore_customization>
                <type>model</type>                           
                    <class>customization/observer</class>
                    <method>saveCustomerCustomizationData</method>
            </electronicsstore_customization>
        </observers>
    </adminhtml_customer_save_after>
</events>

Also do not forget to clear cache.

With sales_order_shipment_save_commit_after you will run into the same issue. The other mentioned events do not tell if the shipment was/will be created successfully.

Probably the sales_order_shipment_save_after event is just fine, but you miss a point: The save() method is not only called on create operations but also on update. In your case, I guess, the latter fires on invoice creation.

Stick with the event and test in your observer method whether the shipment was just created or not:

// Observer::shipmentSaveAfter()
if ($observer->getShipment()->getOrigData('entity_id')) {
    // shipment updated, do nothing
    return;
}

// shipment new, send text message

This is not 100% reliable though as the original data is populated on load and as such not necessarily during multiple calls to the save() method.

Alternatively you could register a flag on sales_order_shipment_save_before:

// Observer::shipmentSaveBefore()
if ($observer->getShipment()->isObjectNew()) {
    Mage::register('send_shipment_message', true);
}


// Observer::shipmentSaveAfter()
if (!Mage::registry('send_shipment_message')) {
    // shipment updated, do nothing
    return;
}

Mage::unregister('send_shipment_message');
// shipment new, send text message