You can have only one email address in your Todoist account and receive email reminders just to this one address. You could of course use someone else's phone number for SMS reminders, but there's currently no support for multiple email addresses.
Both reminders would be for me (work and personal email) to keep work and personal use separate. I don't want my 'Feed the cat' reminders appearing in my work inbox. I think a personal SMS and a work email will suffice but it would be nice to have the option. Think I will suggest it on your wishlist.
Thanks for your quick help David,