Can I use more than 1 address in a sustainer account, or is it 1 email per account?
You do not need a sustainer account to do this. You can use more than one address by separating them with commas.
Say the two devices you want to send to are:
In Push to Kindle’s ‘send to’ field, you’d enter:
You can do this for up to 5 addresses.
You can only set one ‘send from’ address in Push to Kindle, so if these two devices are registered to the same account, make sure the ‘send from’ address appears in your Kindle approved list (you can set this in Amazon’s Manage my Kindle pages). If these addresses belong to two separate accounts, you’ll need to make sure the ‘send from’ address you use in Push to Kindle appears in the approved list of both accounts.
Hope that’s some help.