What is postmortem.report?
postmortem.report is a set of free tools that read the thing that broke. You paste a bounce message, a raw mail header or the output of a server check, and you get a plain reading back. The home page says each reader "runs on your machine and every finding points at the exact text it came from."
We built it and we run it. It is free. There is no account and no sales call.
What can a business owner check with it today?
Six things, all in the browser. The home page lists a bounce reader, a dcdiag reader for Windows domain controllers, a mail header reader, an email safety check, a domain check and a password check.
The two that most owners will use are the email safety check and the domain check. The email check takes a whole suspicious message and gives "a straight answer on whether to trust it." The domain check asks one question: can someone send email as your domain? It reads four public records, shows each one exactly as it came back, then says what it means in plain English.
Why does it not upload what you paste?
Because we do not want your email. If we never receive it, we cannot lose it.
The readers are compiled to WebAssembly and run in your browser. The site's engine manifest lists four of them: bounce, dcdiag, dmarc and reportedemail. The site names two exceptions and says so plainly: the domain check asks a public DNS service for the records, and the password check sends only the first five characters of a scrambled copy of the password. The match happens on your machine.
How does it avoid giving a false all clear?
It never calls an email safe. The best answer it gives is that nothing fired. The first real email we put through the engine came back "insufficient evidence."
That sounds like a failure. It is the design working. A tool that guesses "safe" is worse than one that says it does not know. There is also no score out of 100. A score hides the reasoning, so you get findings and the evidence behind each one.
What is the engine underneath?
It is called mailautopsy, and it is open source. It is a Go library and command line tool with no outside dependencies, under the MIT license. Version 0.1.0 went out on July 25, 2026, according to the mailautopsy releases list on GitHub.
Open source matters here. An IT provider can read the code before they point a client at it. The same input gives the same verdict every time.
What broke along the way?
Google was not reading the site at all. Our own indexing notes from September 4, 2026 found that Googlebot fetched robots.txt ten times in 96 hours and never fetched a page. Nothing was blocking it. The site had never been set up in Search Console, and the home page linked to only one section.
The fix was plain work. The home page now links to all five reference sections. The site's sitemap listed 263 pages when we read it on November 4, 2026, including 159 mail error pages.
The first version was also the wrong shape. We retired a web app from July, and the site is now plain static pages built with Node's standard library.
What did we keep?
Three habits we would bring to any client system.
First, every deploy checks itself. Each deploy backs up the live site, checks the new pages byte for byte over HTTPS, and restores the backup if anything fails.
Second, dates tell the truth. The sitemap takes each page's date from its last real change, not the build clock, so a rebuild that changes nothing does not tell a crawler that ninety eight pages moved.
Third, every answer shows its evidence. Each reference page says what a message means, who has to fix it, the fix in one line and how to prove the fix worked.
Why should a business owner care?
Because it is a fair test of how we work. We built a product, put it in public, and wrote down what went wrong. If you are deciding who to trust with your email or your server, you can run a free check and see the work for yourself. You can also read more about postmortem.report on this site.