Can I use my own email service?

Yes — anything that filters wp_mail. Install your SMTP or transactional-email plugin as usual and this plugin's messages go through it with no configuration here.

The launch email comes from your site title unless you type a Sender name in the Launch Email panel, and replies go to your administration email address unless you give a Reply-to address. A sender name your email plugin sets for the whole site is kept when the field is empty.