Welcome back to the Deep Dive. This is the show where we take that stack of
documentation you sent
our way, articles, specs, you name it, and we boil it all down into the knowledge
you actually need.
And our focus today is on a really fascinating piece of open source software called
DavMail.
Our mission here is to explain for a beginner what happens when you try to use a
standard tool
like Thunderbird with a big proprietary system like Microsoft Exchange.
We're going to get into the technical conflicts, the clever translations, and the
pretty urgent
future this software is facing, all based on the DavMail project docs we have in
front of us.
It's all about why a translation layer like this is so necessary.
Before we dive in though, this knowledge extraction is made possible by SameServer.
They handle the hosting of complex software and support your digital transformation.
You can find out more at www.safeserver.de.
All right, let's get into it.
Okay, so let's just start with the core motivation here.
The documentation says, and I love this, that a key goal is to get rid of Outlook.
I mean, that statement alone really captures the whole conflict, doesn't it?
It really does. It gets right to the heart of the matter.
It all comes down to vendor lock-in and, well, proprietary communication.
When a company decides to use Microsoft Exchange,
they're not just choosing an email program.
They're buying into an entire ecosystem.
Exactly. An ecosystem that relies on its own closed private ways of doing things.
It's not using the open languages of the internet for calendars or contacts.
It's using Microsoft's specific protocols.
So the problem isn't just the app on your computer.
It's the actual technical handshake happening between your machine and the server.
That's it. It's like, imagine you speak perfect English, a universal standard,
but the server you need to talk to only accepts requests
in a very, very specific proprietary dialect of Klingon.
A standard email client just wouldn't know what to do.
It'd hit a technical wall immediately.
The server just won't recognize its request for, say, your calendar or your mail
folders.
And this is where DavMail gets really clever.
The documentation says it works by using Outlook Web Access, or OWA.
Why is OWA the key to unlocking this?
It's such a smart approach.
DavMail basically uses Microsoft's own web portal as the bridge.
OWA is designed so that anyone can access their exchange account from a web browser,
which means it provides a known entry point.
Ah, so it doesn't have to crack the deepest, most complex desktop protocols?
Precisely.
It just finds that OWA link and uses that pathway to talk to the exchange server.
It works even if you're outside the company firewall.
So instead of trying to break into the main vault,
DavMail just walks through the public-facing web portal that was already built for
remote access.
And it acts as the interpreter for everything.
Its whole mission is stated so clearly.
Provides standard compliant protocols in front of proprietary exchange.
It's an open source translator.
Okay, let's unpack that translation work because the documentation lists six key
open standards.
And for a beginner, this might just sound like, you know, alphabet soup.
We've got POP, IMP, SMTP, CalDAV, CardDAV, and LDF.
It does sound like a lot, but it's actually a very logical stack.
You can think of DavMail as a specialized switchboard
routing different types of information using these universal standards.
So where do we start? Email, I assume.
Right. The most common one today is IMAP, the Internet Message Access Protocol.
DavMail translates Exchange folders into IMAP so your client can see everything,
not just your inbox, your sent mail, your archive folders, all of it.
That's why your email looks the same on your phone and on your laptop.
Exactly. DavMail makes Exchange just look like a standard IMAP server.
And what about POP? That's an older one, right?
Correct. POP, or Post Office Protocol, is much simpler.
DavMail still supports it, but it typically only lets you download messages from
your inbox.
It's for a more basic setup.
Okay, so IMAP and POP let us pull mail down. How do we send it back out?
That would be SMTP, the Simple Mail Transfer Protocol.
That handles all of your outgoing mail.
So DavMail takes your message, translates it, and hands it off to the Exchange
server using SMTP.
Those three cover all your core email functions.
This is where DavMail becomes more than just an email tool. It integrates
everything else.
Let's talk about calendars and contacts.
Yes. For your calendar, you have CalDAV. This is the open standard for scheduling.
It's what allows an app like Apple's iCal or Thunderbird with the Lightning
extension
to read and write appointments on that Exchange server.
So if CalDAV is for the calendar, I'm guessing Cardav is for contacts.
You got it. Cardav is for synchronizing your personal contacts.
It makes sure that the address book on your local client is always up to date with
what you have
stored in Exchange. That's your personal address book. But in a big company, you
need to be able
to find anyone. You need the global address book. And that is the final piece of
the puzzle.
That's handled by LDAP, the Lightweight Directory Access Protocol.
This is a really powerful feature. DAVmail uses LDAP to give you access to the
entire company
directory. So when you start typing someone's name in the To field... LDAP is what's
looking
that person up in the corporate directory and completing their email address for
you.
Without it, you'd be completely blind to everyone else in your organization.
That one feature is what really makes it feel like a professional,
fully integrated tool, not just some workaround.
It really is. And the way it's built is just as important. The documentation notes
that it's
implemented in Java. Which is key because that's why it should run on any platform,
right?
That's the whole idea behind it. That platform independence is central to its whole
philosophy.
It's tested and released for Windows, for Linux Ubuntu specifically, and for Mac OS
X.
So it's truly cross-platform.
And it even goes beyond the desktop. They mentioned successful tests connecting an
iPhone,
provided DavMail is running on a central server.
So it can be a gateway for an entire organization, not just one person.
Okay, but this is where the documentation gets really surprising. And it gives you
a sense of
just how serious this project is. It's not just a hobbyist project.
No, not at all. This detail is really important. The sources explicitly state that
the CardDAV
implementation, the contact syncing part we just talked about, was sponsored by the
French Defense,
the DGA, through a project called Trusted Bird.
Wait, wait, the French Ministry of Defense, a national defense agency sponsored a
feature
for an open source email gateway. Why would they do that?
It tells you everything you need to know about the strategic importance of this.
For a defense organization, being totally dependent on a single,
closed, proprietary system is a massive systemic risk.
They want to avoid vendor lock-in for security reasons.
Exactly. By funding the CardDAV part, they were ensuring they could use secure,
open source clients that they could audit themselves. It elevates DAV mail from
just
a cool community project to, well, a matter of strategic institutional security.
That really drives the point home. And just to be clear, we're looking at a very
recent version
here, 6.5.1, published October 29th, 2025. This is a very active project.
And it has to be. Because DAV mail is in a constant involuntary race against
Microsoft's
own evolution. The roadmap really lays out the project's existential threat and its
plan for
survival. And that brings us to the most critical thing on that roadmap, the jump
to version 7.0.
This isn't just a regular update, is it? No, it's completely mandatory. It's the
single most
important thing in the entire document. Right now, DAV mail's backend relies on
something
called EWS or Exchange Web Services. And what's the problem?
The problem is Microsoft has deprecated EWS. They're going to remove it entirely.
And when
they flip that switch, the current version of DAV mail will just stop working.
Period.
So this is a total rebuild of the foundation just to keep the lights on.
That's it, exactly. Microsoft is pushing everyone to their new graph API. So DAV
mail team is now
forced to implement a brand new, very complex graph API backend in version 7.0.0
just to
maintain the functionality they already have. That feels like a never-ending game
of whack-a-mole.
If Microsoft keeps moving the goalposts like this, is relying on a gateway like DAV
mail
an inherently risky strategy for a company? That is the core tension. It's a
calculated risk.
The benefit is you get freedom of choice for your clients. But the cost is this
perpetual
maintenance cycle, relying on the DAV mail team to constantly chase whatever
changes Microsoft makes.
And if they can't keep up? The gateway fails. The roadmap does mention some other
things
they're considering, though, once the big graph API transition is done. Yeah, they're
looking at
quality of life improvements. Things like using a new OVBRS endpoint, adding CalDAV
attachments,
better IMAP folder management. But all of that is secondary to the main survival
effort. And it's
also clear about what they are not doing, what's been explicitly ruled out. They've
made some hard
choices. They're not implementing the ActiveSync backend, which a lot of mobile
devices use.
They're also not adding instant messaging or chat. They're staying laser focused on
email,
calendar, and context. It makes sense. You have to focus your resources when you're
facing that kind
of mandatory rebuild. You absolutely do. It really shows that open source freedom
comes with the price
of constant vigilance. So let's wrap this up. For you, the listener, I think the
core takeaway here
is that DavMail is this crucial open source translator. It gives you freedom,
letting you
use the client you want in the lockdown world of Microsoft Exchange. But that
freedom isn't free.
It has to be constantly defended through these huge technical efforts, like the
mandatory shift
to the graph API. It's a constant battle. Which leaves you with a really important
question to
think about. If adopting this new API means DavMail is always playing on Microsoft's
home turf
by Microsoft's rules, what happens if Microsoft decides to change those rules every
six months?
Can an open source project ever guarantee long-term stability when faced with that
kind
of mandated obsolescence? A question of digital sovereignty, really. That's a
perfect thought to
end on. This deep dive was supported by Safe Server, helping you with hosting and
digital
transformation solutions. Learn more at www.safeserver.de. We hope this gives you a
shortcut to being well informed.