multiple email account? Not really. It is typically implemented using some email proxy or alias like anonaddy or simplelogin. By the look of it is multiple accounts, but in fact you’re just receiving mail forwarded to you in one account. All you have to do is append any strings as the user with your domain.
(anonaddy and simplelogin requires adhoc address generation using subdomain by them or a domain owned by you with MX records pointing to their servers)
disclosure: I’m a current customer of anonaddy. Never used simplelogin though.