Error email Alias

Dears infra team I try to help my friend to email alias fp.o problems but I am having problems. when sending an email to the address contained an error, as below, please help him on this issue fas information: suba(a)fedoraproject.org ----- Delivery to the following recipient failed permanently: suba(a)fedoraproject.org Technical details of permanent failure: Google tried to deliver your message, but it was rejected by the recipient domain. We recommend contacting the other email provider for further information about the cause of this error. The error that the other server returned was: 550 550 5.1.1 <suba@fedoraproject.org>... < suba(a)fedoraproject.org&gt;: Recipient address rejected: User unknown in local recipient table (state 13). -- Regards, ekoikhyar* ***PGP : 4EA60FFA< http://pgp.surfnet.nl:11371/pks/lookup?op=index&search=0x4EA60FFA> t: @FedoraIndonesia | w: http://id.fedoracommunity.org/*