Hi @mike_lewis
There certainly is a way of adding email addresses for your customers, the following post explains how you do that: Add a new client
However, there currently isn’t a way for this to be done with suppliers, but there is a feature request for it that you might want to add your vote to: Additional supplier email addresses and contacts
I’m sorry I couldn’t be of more help on this occasion, but if you have any further questions, please don’t hesitate to ask.