Hi,
Q2A already has this facility. You can override the content of the emails using the translation system:
http://www.question2answer.org/translate.php 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.
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