Milestone: Send and Receive Email

In this milestone you will send (and receive) your first email. Before you begin you should verify your MX and SPF records are in place using dig. If they’re not don’t try to send email, you will poison DNS and have to wait for the TTL to expire on your broken DNS records.

Updated Firewall

Remember, your must update your Firewall before this will work. The following chains should be updated from your previous configuration to look like this:

IPv6 FORWARD Chain (Policy: DROP)

Rule Selection Target
1 Input from device ens224, output to ens192 ACCEPT
2 ICMPv6 Protocol ACCEPT
3 NEW packets to TCP port 22 ACCEPT
4 NEW packets to TCP port 25 of infra ACCEPT
6 UDP/53 to the IPv6 of infra ACCEPT
7 ALL packets LOG

Install Alpine and Send me Email

Install the command line MUA called alpine:

infra$ sudo apt install alpine

Once you have alpine installed send email to yourself at Opus:


Alpine is installed on Opus. When you can receive and reply to your own email, send an email to me:

Send Yourself Email

Use your existing personal account (e.g. Gmail) to send email to yourself on your own domain:


If your DNS, firewall and Postfix are setup properly you will receive the email. When you have forward it to me at my Opus address.

Turn In

  • Copy-and-paste the emails you sent me into Canvas (I will verify it on Opus)

Submit your homework on canvas.