Don't bother trying to answer my above question.
After thinking about it I don't think I can improve the first select.

It's for an email notification system which will be run by a cron job every night at times of least usage. It will be slow as it will need to send a large amount of email. I'll use SET SQL_BUFFER_RESULT to free up table locks. Is there anything else I can do to to speed things up?

thanks

Bob