I'm trying to setup a simple email server using node smtp-server. I'm the only one that's ever accessed the machine (a CentOS 6.5 box on Digital Ocean), and I've only set up 2 http servers. I'm getting the error "EADDRINUSE" when I try to listen on port 25.
lsof | grep smtp gives me:
master 955 root 12u IPv4 8103 0t0 TCP localhost:smtp (LISTEN) master 955 root 13u IPv6 8105 0t0 TCP localhost:smtp (LISTEN) master 955 root 53u unix 0xffff88003a91c380 0t0 8155 private/smtp
What might be using port 25, and how can I disable it?