Cirrux Update – Mail Beta, calendar sharing and more / Cirrux

Hi everyone,

Thanks for following along! It's been a few weeks since the last update, so here's an overview of the biggest changes.

Before diving in: I was a guest at the Dutch podcast 'De Grote Techshow' which was fun (and pretty technical). If you want to hear me talk about Cirrux, you can find it here.

And secondly: if you need any help to make the switch, whether it is to configure your domain or if you're worried about migrating your data--do reach out. More than happy to see what I can do to make it easier.

Let's dive in! There's a lot to talk about.

Share calendars between any Cirrux user

You can now easily invite any other Cirrux user to share a calendar. Add by email, which will send out an invite the other person can then accept.

Manage mailboxes → Calendars → Manage sharing

Secondary MX: backup mail delivery

While receiving email is not as complicated as sending it, there are scenarios where my mail server is temporarily unreachable. For that reason I've added a secondary server that runs independent from the rest of the system.

If you want to make use of that, you'll need to adjust your DNS settings. The most up to date records you can find in your domain settings.

Email security improvements

A lot happened under the hood to make Cirrux's email infrastructure more robust and standards-compliant. Feel free to skip this section if you're not an email nerd.

MTA-STS inbound — Cirrux now publishes an MTA-STS policy, telling other mail servers to only deliver over encrypted connections and reject sending if the encryption fails. This is active for cirrux.me domains automatically, and I'm happy to help set it up for your custom domain.
DKIM via CNAME — New domains can now set up DKIM signing with a single CNAME record instead of copying a long TXT value. No change required if you already have your custom domain running, it's just a nice upgrade that makes it slightly easier for new folks.
DMARC set to reject — DMARC signals to other servers what to do if they get emails from Cirrux that look suspicious. After testing my setup for a few months I now switched it to the strictest possible setting.
SPF HELO-first checking — Now compliant with RFC 7208's recommendation to check the HELO identity before the envelope sender
ARC validation — The spam filter now recognizes ARC (Authenticated Received Chain) signatures, reducing false positives for forwarded emails
Improved spam detection — New rules for gibberish domains, crypto keywords, domain age checks, and envelope sender mismatches.

Notable other fixes and improvements

CalDAV performance is significantly improved for faster syncing and loading in your clients
Improved IMAP rate limiting which was sometimes flagging legitimate use
Improved IMAP change synchronization: archiving, moving and deleting emails now shows up instantly across your devices
Fixed recurring calendar event cancellation emails showing wrong dates
Password reset now also confirms your email address
Improved security of the platform: I'm now monitoring outbound email traffic to make sure there's no spam going out or clients going rogue

Beta: Cirrux Webmail

Saving the best for last. While I love that you can bring any open-standards compatible client to Cirrux (and I'll continue to support that), I always wanted to run my own clients too. When I asked the Superfans in the Telegram group, the answer was clear: please start with mail. So that's what I did.

This is what it looks like:

You can read, write, reply, organize and search your inbox. It sits on the same infrastructure as the IMAP server, so you can use those side by side (I don't have a mobile app yet, so for mobile access you'll want to continue using whichever app you're using today). It's built for speed, fully keyboard accessible and I'm syncing your changes so you can continue working on your email if there's no internet connection available.

It's in Beta today, and I'm prioritizing access to Superfans 💜. Want to make the switch and get early access? You can upgrade to Superfan with two clicks if you aren't one already.

Next up

Primary focus is making Cirrux Mail available to everyone as quickly as possible. After that, file sharing is next.

As always, let me know if you run into anything or have feedback.

Have a great rest of your week!

Rick