The tab “Supporters” on your project (just above your main picture) is a public list with all usernames of your contributors.
As a project owner, you also have access to a detailed list in your toolbox, from the section “My supporters”. There are listed (and available for export under excel and csv format) the full names, email addresses, contribution amount and selected reward.
If you wish to contact them, you can create a private news. All news are automatically sent by email to your supporters. It’s an easy and fast way to communicate about your campaign.
If you need to contact a specific user you can also use Ulule messages. You can go to the user profile and send him/her a message.