Thunderbird DAV autoconfig

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The Basics

  • Nextcloud Server version (e.g., 29.x.x):
    • 32.0.1
  • Operating system and version (e.g., Ubuntu 24.04):
    • Ubuntu 22.04.5 LTS
  • Web server and version (e.g, Apache 2.4.25):
    • Apache/2.4.52 (Ubuntu)
  • Reverse proxy and version _(e.g. nginx 1.27.2)
    • Zoraxy 3.2.5
  • PHP version (e.g, 8.3):
    • 8.3
  • Installation method (e.g. AlO, NCP, Bare Metal/Archive, etc.)
    • Manual
  • Are you using CloudfIare, mod_security, or similar? (Yes / No)
    • No

Summary of the issue you are facing:

Hello, and sorry for deleting the rest of the template - my question doesn’t seem to fit it. I was unsure about whether should I put it in Support category, but the General category template warned me that I shouldn’t put any technical questions there.

I recently have configured my email server and now I’m trying to set up autoconfig for Thunderbird, so when a user logs in, their contacts and calendars from Nextcloud DAV were automatically added.

I’ve followed this doc:

https://wiki.mozilla.org/Thunderbird:Autoconfiguration:ConfigFileFormat

and managed to get at least the calendar to connect, but with one unfortunate condition: I have to open Thunderbird’s about:config and set browser.opaqueResponseBlocking and browser.opaqueResponseBlocking.javascriptValidator to false.

Otherwise the request to DAV gets blocked by Thunderbird for some reason. Here is some information about my current setup: IMAP and SMTP servers are located at mail.mydomain.com, and email addresses look like user@mydomain.com. The webserver serving config-v1.1.xml is located there too, but it’s behind a reverse proxy, which also proxies nextcloud.mydomain.com. When I add a new account to Thunderbird, it requests mydomain.com/.well-known/autoconfig/mail/config-v1.1.xml, so I’ve added a redirection rule on the reverse proxy which sends it to mail.mydomain.com and it seems to be working ok. I’ve added this section to the xml file:

   <addressBook type="carddav">
     <username>%EMAILLOCALPART%</username>
     <authentication>http-basic</authentication>
     <serverURL>https://nextcloud.mydomain.com/remote.php/dav/</serverURL>
   </addressBook>

   <calendar type="caldav">
     <username>%EMAILLOCALPART%</username>
     <authentication>http-basic</authentication>
     <serverURL>https://nextcloud.mydomain.com/remote.php/dav/</serverURL>
   </calendar>

(username on the Nextcloud matches the local part of the email address)

But looking at Network tab of the dev console I can still see that it’s trying to get well-known dav from my top level domain. So I add a redirection from there too:

mydomain.com/.well-known/caldav -> https://nextcloud.mydomain.com

mydomain.com/.well-known/carddav -> https://nextcloud.mydomain.com

Finally I can see the request is made to the correct address:

207 PROPFIND nextcloud.mydomain.com/remote.php/dav

But the icon shows it’s blocked and there is a message in the JS console:

The resource at “https://nextcloud.mydomain.com/remote.php/dav” was blocked by OpaqueResponseBlocking. Reason: “nosniff is true and mimeType is an opaque-blocklisted MIME type or its essence is ‘text/plain’”.

I’ve found 2 settings I can switch off:

browser.opaqueResponseBlocking = false browser.opaqueResponseBlocking.javascriptValidator = false

And after that, viola - I can see my calendars showing up upon adding the account (but not contacts, I think it’s a separate issue and I have to check everything).

Some searching suggests that I could modify content-security-policy header, but also that is not a good idea and Nextcloud sets this header automatically.

I think the soultion would be to add my root domain to connect-src and script-src.

But is there a correct way to do this?

1 Like
2

Looking at the request and response headers, I notice that Thunderbird expects
Accept: text/xml

But Nextcloud responds with

content-type: application/xml; charset=utf-8

Could this be the source of the problem?

3

Ok, I’ve figured it out.
config-v1.1.xml addressBook and calendar sections don’t do anything, Thunderbird will always request the domain the email address is on.
Unfortunately, looks like the is no way to relax policies by adding my root domain to Access-Control-Allow-Origin, so you can’t use redirects. I’ve ended up doing it like this:

  1. Add virtual directory remote.php/dav for the root domain on the reverse proxy, pointing to remote.php/dav of my Nextcloud’s internal IP

  2. Add my root domain to trusted_domains in config.php

1 Like