You need to setup Mx-records for your domain and/or a mail relay (smtp server) that forwards incoming emails on the domain to your application host and port. Your sysadmin should know how to do this.
(Btw, it is not a Pop3 request, but an smtp request. SMTP is the 'send and deliver protocol', pop3 and imap are just protocols to read the messages of a mailbox from a mail server. That knowledge might improve google results ;-) ).