TECHNICAL NOTES
Things I explain over and over.
A library, not a journal. There are no publication dates here, because a note on configuring DMARC is just as useful a month and a year after it was written. What you get instead is the month it was last checked.
Get in touch- Notes
- 20
- Format
- a library, not a journal
- Topics
- 5
Mail and domain
SPF, DKIM and DMARC — reaching p=reject without losing mail
Three records decide whether anyone can send mail in your company's name — and why the last of them has to be switched on more slowly than it looks.
9 min read · checked: August 2026
Why mail goes to spam when „nothing was changed”
It is almost never about the content of the message. Usually about something that changed outside the company, or has been true for a long time and just crossed a threshold.
8 min read · checked: August 2026
Migrating mail to Microsoft 365 — what to plan before you start
Moving the mailboxes themselves is simple. The cost sits in what nobody remembered: the printer, the invoicing system and two years of mailbox rules.
8 min read · checked: August 2026
Reading DMARC reports so they stop being noise
Reports arrive daily as XML in an archive and are unreadable raw. All of their value sits in one column.
7 min read · checked: August 2026
Security
Local administrator rights — the single change that matters most
The cheapest thing you can do for a company's security, and at the same time the one that meets the most resistance. Usually undeservedly.
7 min read · checked: August 2026
Five things that improve security and cost nothing
Most incidents in small companies do not come from missing tools but from unfinished configuration of the ones already in place.
8 min read · checked: August 2026
An incident response plan that fits on one page
Nobody reads a thirty-page document under pressure. One sheet by the desk changes the first hour more than anything else.
6 min read · checked: August 2026
MFA in a small company — where to start and what not to switch on
MFA is included in every serious office suite. The problem is not that it is missing — it is that it is not switched on.
7 min read · checked: August 2026
Antivirus is everywhere and the console has been silent for months
The company pays for protection on every workstation. The console shows that some agents have not checked in for six months. This is not a rare case.
6 min read · checked: August 2026
Order in the environment
The old system you cannot replace — how to live with it
Every guide says „replace it”. This one is about the situation where you cannot, and the machine still has to run for another three years.
9 min read · checked: August 2026
Offboarding an employee — the list of things to close
In every environment I look at for the first time there is an active account belonging to somebody who has left. Usually more than one.
6 min read · checked: August 2026
How many cloud services do you pay for? An inventory that pays
Subscriptions were bought by different people at different times, and they renew themselves. The list usually comes out longer than anyone assumed.
7 min read · checked: August 2026
How to establish what in the company no longer gets patches
The most underrated risk in small companies. Not because it is hard to fix — because nobody knows it is there.
6 min read · checked: August 2026
IT documentation nobody reads — and the kind that saves the day
Documentation loses not because it is missing, but because it is written as an obligation instead of as a tool.
6 min read · checked: August 2026
Servers and backups
„We have backups” versus „we can restore”
Almost every company has backups. Far fewer know how long a restore takes, or whether it will work at all.
8 min read · checked: August 2026
Your own server behind Cloudflare — closing the back door
Cloudflare hides the server address in DNS but does not block traffic that reaches it another way. If the firewall does not close that, the hiding is cosmetic.
7 min read · checked: August 2026
Monitoring that only wakes you when it should
A system sending a hundred notifications a day informs you of nothing. After a week nobody reads them, and they are right.
6 min read · checked: August 2026
Hosting for a company website — what to check before you sign
Providers' comparison tables talk about disk space and transfer. About what actually hurts, they say nothing.
6 min read · checked: August 2026
Decisions and cooperation
Before you buy another tool — five questions about the one you have
Another licence rarely solves a problem caused by the unfinished configuration of the previous one. Usually it just covers it up.
6 min read · checked: August 2026
Why I insist on a single route for requests
The phone is the fastest way to report something and the worst way to run a case. Those are two different things and worth separating.
5 min read · checked: August 2026
Describe the problem.
You get a straight answer.
No specification required. A few sentences about your company and what currently does not work is enough to start.
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