Setup Postfix + Dovecot + Roundcube (almost a mailserver)

  Outgoing Port 25 blocked!!! Since Hostinger is blocking outgoing port 25 there's no use of full mail-server running on our VPS. But if we want - we can still install install Dovecot (IMAP client)...

Set-up sending mail via gmail account

This tutorial asumes a scenario that we bought a VPS for our own little business like online shopping or a portal,  that won't fit in shared hosting, therfore you don't need to setup full in-and-out mailserver...