Setting up your own authoritative DNS server jots

What’s this? These are somewhat random jots I made while setting up an authoritative BIND server, so that a simple VPS machine can function standalone. Well, almost standalone, as it takes some help from a slave DNS to supply the second DNS entry. But even if that slave goes away suddenly, the show will go [...]

The art of setting up a sendmail server on Debian 8

But why? Fact number one: Running your own mail server is the most likely cause for messing up, and that can mean an intrusion to the server or just turning it into a public toilet for spam. Nevertheless, if mail delivery is important to you, there’s probably no way around. And I’m not talking about [...]

Digging to the root with DNS queries

Introduction This is an explicit walkthrough on how a domain name is resolved. Doing the recursion manually, that is. And then some remarks on the mess with DNS glue records. Getting the root servers $ dig NS . ; <<>> DiG 9.11.3-1ubuntu1.2-Ubuntu <<>> NS . ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: [...]

Gmail: How to turn off spam filter for incoming mails

Gmail is definitely the leader in the field of email services, and their spam filter is actually very good. From my own experience with setting up a mail server, I can tell that it’s not all that easy to make Gmail’s incoming mail servers even talk with you. So the larger part of spammer don’t [...]

The SPF, DKIM and DMARC trio: Making your email appear decent

Intro Whether you just want your non-Gmail personal email to get through, or you have a website that produces transactional emails (those sent by your site or web app), there’s a long fight with spam filters ahead. The war against unsolicited emails will probably go on as long as email is used, and it’s an [...]

SMTP tidbits for the to-be postmaster

This is a quick overview of the parts of an SMTP session that are relevant to SPF and mail server setup. Just a sample SMTP session For a starter, this is what an ESMTP session between two mail servers talking on port 25 can look like (shamelessly copied from this post, which also shows how [...]