Developer and owner for example, or distribution company and manufacture. I have a couple manufacturing clients that took some sort of distribution deal, where the distributor is paying for the web hosting, but it was originally set up with the manufacturing client. It's possible the distributor only needs to see the invoices now, but unless they tell me otherwise, I'd want to send it to both contacts, there are other reasons for multiple contact emails, some clients can be a bit confusing, emailing from multiple email addresses, and it's not clear which email is their main email, better to email all 3 of their emails if they aren't making it clear which is the one they actually check. Maybe nitpicking, I'm just trying to get this finally set up and automated and people paying! System makes it easy to add additional phone numbers, not that I need to put any in Blesta, additional emails would be great.