Q2A already has this facility. You can override the content of the emails using the translation system:
The file you will want to translate is qa-lang-emails.php.
If you want to send an additional email on registration, the next version (1.4) of Q2A will feature an event API that allows you to write handler code which is called when a user registers.
Welcome to the Q&A site for Question2Answer.
If you have a question about Q2A, please ask here, in English.
To report a bug, please create a new issue on Github or ask a question here with the bug tag.
If you just want to try Q2A, please use the demo site.
April 20, 2021: Q2A 1.8.6 released!