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Old 23 Aug 2015, 08:35 AM   #1
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Join Date: Mar 2002
Location: Wicklow, Ireland
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Fun with CardDAV

One of the prices of loyalty to Fastmail in recent years has been the following:

Spouse: Can you help me with my email addressbook? I've got hundreds of copies of some addresses again and... (once in a while it was thousands)

The cause: glitches with an extension for Thunderbird for syncing contacts with Google (used to keep her Thunderbird address book and Android phone in sync via Google).

It may be too soon to consider all that as receding in the rear view mirror BUT, by a happy coincidence with Fastmail's announcement of CardDAV being officially supported, my wife and I now each have a shared address book as well as individual address books and, in my wife's case, a private one (for her clients), on our own CardDAV server.

As users of a family account with Fastmail we could have had a shared addressbook using the masteruser account for some time, but it wasn't worth the effort to try to manage this manually. So we continued with overlapping addressbooks that were quite often out of sync on records we'd have happily shared.

Naturally, what we'd have liked to have was, and is
  1. Contact data synced across desktop/phone/web clients
  2. Shared contacts synced between accounts

Here's what I did:

I run a Synology storage box at home (a DS413). This is capable of running a CardDAV server and one is as easily installed as an app on one's phone. Unfortunately, the default one is not very good. It uses Postgres for storing data, which is overkill for a family rolodex running on a small box, and it is set up to rely on a 1:1 correspondence between addressbooks and users (an extra address book requires an extra user). It's also so poorly supported by Synology that it is, I think, the only official app that doesn't have a support forum section on Synology's web site. I switched to a brilliant alternative called Baikal. It's open source, small, fast and, just sweet. It can use Mariadb/MySQL or SQLite for data. It simply worked immediately where the official CardDAV server had failed. In fairness, quite a few of the problems I had were with Sogo, a Thunderbird CardDAV extension, more on which in a moment.

First, I should say that what enabled me to get syncing to and from our own data source working in the first place was buying an SSL certificate and installing in the Synology box so that data exchanges, including remote logins, would be encrypted. Previously I didn't do enough remote logging in to really justify investing the time and effort (I just used SSH and SFTP occasionally). It's not difficult to do (some links on installing an SSL cert are appended). An SSL cert costs about $9/yr from

Like many Fastmail users I own my own domain, and by virtue of installing the certificate could now access it using https not just http. This involved pointing the domain to my fixed IP address (leaving the MX records pointing to Fastmail), but owning one of these isn't necessary. Plenty of people point an alias to a dyanimc DNS name (instructions in the links below).

By far the greatest difficulty I had getting things set up once I'd installed Baikal (the installation and configuration instructions are excellent and very simple) was getting the Thunderbird extension Sogo to actually work. This was SUFFICIENTLY maddening that I thought I ought to post about it here to save anyone else the trouble I suffered with it.

First, I got it working on my Linux laptop. I found that it was temperamental about whether it would synchronize but worked well when it did. Then I got it working on my Windows laptop. On my wife's laptop it simply wouldn't work at all. I ended up completely reinstalling Thunderbird, and in the course of doing so I discovered that Mozilla had secretly installed some stuff I had known nothing about (TestPilot extension), and there looked to be a few years worth of cruft there as well, related to extensions tried and then abandoned, and some other indecipherable things. In addition, there was a brand new Mozilla Services extension that I appeared to have installed just now without knowing and which apparently can update software behind your back (with no UAC interaction). [Having just been through some grief blocking the 100% unwanted Windows 10 reminders on our computers this was unwelcome, putting it mildly].

With a reinstalled Thunderbird... Sogo worked. Almost.

I found that it would not sync with two CardDAV addressbooks belonging to the same user on the same server using different address books. Switching to an IP address and a domain name for separate address books resolved, but this was not very satisfactory solution. Then I stumbled over the fact that using (and forwarding) a different port for each would resolve the problem, like magic, including specifying port 443 (redundantly of course). Thus,




were seen as different by Sogo. Without the difference it refused to request credentials and without credentials it wouldn't sync an additional addressbook.

On my phone I'm using a free app called CalDAV-Sync that also seems to "just work". I'll probably upgrade it to the paid version (I made a first donation to the author of Baikal) once I have figured out the remaining synchronizations I want to manage, principally with Fastmail (the free version doesn't sync organization or position description information). For now the focus is on tidying up our address books with the possibilty of ending forever the business of being out of sync within the family, then covering all the platforms (phone/web/desktop in that order).

The fact that we'll end up with greater control of our own information is a welcome bonus (not dependent on Google, Apple, Fastmail or anyone else). Yes, Google will still get to know and make use of what's in our Android phones. For now.

If Fastmail will just enable sorting addresses by nickname with the web app I'll be happier still. After that being able to sync distribution list membership, somehow, would be a great extension to CardDAV.

Meanwhile, big thanks to all at Fastmail who delivered CardDAV.

In a world where the likes of Microsoft decides what it wants you to have on your computer, whether you like it or not, it's nice to have options based on open standards.

Installing an SSL certificate


While I've used a Synology box to implement Baikal it's not necessary to own one. It's just a very nice Linux appliance that makes implementing a CardDAV server (e.g.) point-and-shoot simple. Baikal can also be run on a $25 Raspberry Pi. And Synology's software can be run, Hackintosh style, on other hardware, including an old PC (look for YouTube videos on Xpenology).
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Old 25 Aug 2015, 04:42 AM   #2
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It turns out that the restriction on logging in to a server more than once is a known issue and a problem with Lightning (the CalDAV extension) which is used for authentication, not with Sogo Connector.

A pity that the docs for neither Sogo Connector nor Baikal (nor any Google search I did) turned up this fact. One solution suggested by Sogo support is to hack one's hostnames file to sent Sogo to the same destination using different network addresses.
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Old 23 Oct 2018, 10:27 AM   #3
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Why use the synology device, it's it only a sorting issue? Does the baikai sync with fastmail carddav ?
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Old 24 Oct 2018, 12:30 AM   #4
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> Why use the Synology device?

Because it's what I use for storing my data on. And the issue was not the device it was the Lightning software. I posted to save anyone else the hassle of finding it out the hard way.

> Does Baikal sync with Fastmail CardDAV?

It's ages since I set it up (years) so I don't recall much detail about it. I use it with the Thunderbird add on called Cardbook which is excellent and can sync with both.

However, I wouldn't recommend adopting Baikal at this point. It's based on sabre/dav tools ( that are no longer supported or maintained. I will likely be looking at moving to a Nextcloud setup. Just haven't gotten around to it yet.
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