Proton mail and calendar have become really important planks on my quest to tighten up security across all my data and comms. I applaud the efforts Pronton has made to offer security in contacts.... but, its proprietary-only nature basically makes it useless in a modern context when trying to juggle work, home, and businesses and keep it all organised in a place together - namely my native (iOS) contacts app for use by phone dialler, messaging apps, calendar, etc.

As far as I can see, EteSync provides the closest thing possible to what I think many would find incredibly useful. Security and syncing across services. I'm just regular folk..... non-tech... maybe there are some security tradeoffs? I haven't got the knowledge to pick a fight there. But, adopting security-minded solutions has to be accessible and USEFUL. And Proton contacts approach today just isn't at all.

Integration of an EteSync server is a fantastic idea. Or ProtonMail could make a dedicated Android Contacts app to sync with the cloud. The inability to backup, manage, and sync contacts between Android phones and ProtonMail accounts is very problematic, and the one thing that has kept me from completely ditching Google.

@Andrea Moro A year late, but still beneficial to other users.

The ProtonMail Android app does not synchronize your contacts with your Android address book. It simply makes the contacts you have stored in ProtonMail's web client available inside the mobile client. In addition the ProtonMail mobile app can also access any contacts you have stored in the Android address book.

Anyone looking to move away from G Suite will need an alternative to synchronization of contacts, tasks, and calendar(s).

EteSync provides a solution for this. You carry on using the same address book and calendar apps you're already using with your Google account, be it the default Android apps, or 3rd party replacements you may have installed instead.

The thing that changes is the backend you synchronize that data with; instead of unencrypted synchronization with Google's server, you will now use end-to-end encrypted synchronization with EteSync's server. That data will no longer synchronize with your Google account, even if you use the Google provided addres book and calendar app, and Google will not have access to that data.

Tasks are an exception since there isn't a real standard for tasks, hence the proliferation of task apps on the Play Store. Some of them synchronize with Google, others with their own proprietary backend (Remember the Milk, for example), and some don't sync with anything. Using tasks with EteSync requires an app that has in-built support for EteSync. Currently there are only two that I know off: OpenTasks and Tasks.org, with the latter supporting a number of different backend for task synchronization such as Nextcloud, EteSync, and their own platform tasks.org.

Since it utilizes your normal addres app, your contacts will be accessible by other apps, like before, and this includes the ProtonMail mobile app. It still won't synchronize that data with your ProtonMail address book, however, but that is exactly what this suggestion is about: utilizing EteSync to synchronize your contacts, calendars, and tasks with your ProtonMail account.

EteSync is an open source platform that provides both a paid hosted and free self-hosted option.

If Proton added support for EteSync we would gain the same flexibility we've got with G Suite and Outlook: synchronization of our PIM data with ProtonMail, only this time end-to-end encrypted.

ProtonMail, ProtonCalendar and ProtonContacts does not provide a real integration with Android or iOS.
This is a real issue when users wants to move from Google products to Proton products.

I now uses Proton as my main email address, to replace my Gmail account.
But I still uses Google Calendar and my contacts are still synchronized with Google as well :-(

The day you provide a real mobile OS integration, I drop google products!

Also in favor, so contacts and calendar are encrypted, outside of mails / drive etc., but still sharable between services with one unique source of truth.

@Aerion so if i understand it correctly, ProtonMail mobile app already does a dual sync with the Android address book. By using Etesync you get those data on etesync server that would then allow you to sync with your computer, correct?

@Guy, it would overcome the hurdle by synchronizing the contacts (and calendar) directly between ProtonMail's address book and your device's address book.

ProtonMail's current contact synchronization only syncs contacts between the web interface and the ProtonMail mobile app. This means that those contacts are not available to any other app on your device, and ProtonMail is not the only app that requires access to contacts.

Currently I have to maintain my ProtonMail contacts separately from my device contacts which I synchronize with Thundebird on my PC using EteSync.

This is a real pain, as on the extremely rare occasions where I use ProtonMail's web client it has happened to me that I didn't have a specific contact available (I didn't have my phone on me), so I had to log into EteSync's web client to retrieve the email address for my contact. Of course I can then save it in my ProtonMail Contacts, but that means if there ever is a change to that contact's details in my phone's address book it won't sync to ProtonMail Contacts; this means I have then have to remember to update that contact separately in ProtonMail Contacts.

I have very little use for web clients as I either use mobile apps or Thunderbird on my desktop. Even when I was on G Suite I hardly ever used their web interface. ProtonMail's contact "synchronization" therefore is useless to me. Using EteSync, however, perfectly suits my needs as it allows for end-to-end encrypted synchronization of my contacts (+ calendar and tasks) between my mobile devices and my desktop, and I can use those contacts in the ProtonMail app as it has access to my device's contacts.

ProtonMail's current contact synchronization is only useful to users who exclusively use webmail and the mobile app.

Hey @Aerion, it's not clear to me how using etesync overcomes the hurdle. Does installing it on my phone mean that any time I add a new contact to Google it automatically gets added to Protonmail? Thanks.

Definitely in favour of this over ProtonMail's own implementation of contact (and future calendar) synchronization.

Not only would this solve the current issue of having to maintain two separate contact lists (one in the web interface, and on on mobile devices), it would also allow the synchronization with 3rd party software such as Thunderbird., without additional effort or resources on Proton's part.