So Mailinator have recently allowed people to use their own domain. You need an account on Mailinator, and you need to go into your Settings and supply the domain name you want to use, you then need to set an MX record in your DNS settings (cloudflare or hosting provider for @) at the nameserver they give you. Wait 24 hours or so. You can then log into Mailinator, and type in any account, if it has received an email, you can view it there.
This is especially useful if you're trying to set up StartSSL, which requires you verify your domain with an email. So you could get an email sent to firstname.lastname@example.org and you can view it from mailinator. You can't reply though. Note, this is only an inbox, however you can set it up to auto forward everything to another email address if you like.
Account is free etc. Enjoy.