I need to send an email after a customer try to save a new address in his address book
You can use below events for customer address.
<event name="customer_address_save_after"> <observer name="customer_addres_after_save_event_observer" instance="Vendor\Extension\Observer\AfterAddressSaveObserver" /> </event>
<event name="customer_address_save_before"> <observer name="customer_address_before_save_event_observer" instance="Vendor\Extension\Observer\BeforeAddressSaveObserver" /> </event>
You should create
etc/frontend/events.xml file in your module and post there event from Dhiren Vasoya comment. Then create the class
Vendor\Extension\Observer\BeforeAddressSaveObserver depending on your event name and send email inside the class. You can google a little and find the way how to send email with custom template and parameters.