How to configure e-mail clients automatically through DNS

Automatic configuration of mail clients

Some email programs/clients make it easy for users to add new mailboxes or email addresses. They include setup assistants that automatically gather all required data and configuration parameters needed to send and receive emails. All the user needs to enter is an email address, a username, and a password.

Email programs such as Thunderbird or Outlook search for this configuration using the following URL:
https://autoconfig.example.com/mail/config-v1.1.xml
In this case, example.com is a placeholder for your domain.

For mailbox, the correct URL is:
https://autoconfig.mailbox.org/mail/config-v1.1.xml

Requirement: Custom domain

A custom domain is usually required for this feature to work. For more information on how to use email addresses with your own domain, please refer to the following article:
Using email addresses with your own domain

DNS settings at your provider

To enable automatic configuration, you need to adjust the DNS settings at your domain provider.

Depending on the provider, the following may vary:

• User interface
• Field names for DNS entries
• Required input format

Refer to your provider’s documentation on how to create SRV records in the DNS settings, or contact your provider’s support team for assistance.

mailbox cannot provide support for DNS configuration at third-party providers.

The example in this article is based on DNS configuration with the provider Hetzner (German provider).

Automatic client configuration for Mozilla Thunderbird and compatible email programs

If you want to use automatic configuration in setup assistants such as those in Thunderbird or KMail, you should include the autoconfig XML file from our web server.

The easiest way to reference this function is by setting a CNAME record and an SRV record in the DNS settings of your domain.

In DNS protocol syntax, the CNAME record for the autoconfig function is:

autoconfig IN CNAME auto.mailbox.org.

Step-by-step instructions:

1. In the DNS console, select the desired domain (zone).
2. Click Add Record and select CNAME as the record type.
3. Enter the following values:
   • Hostname: autoconfig
   • Target: auto.mailbox.org. (with a trailing dot)
4. Save the record.

Once the DNS system has propagated the new entries, Thunderbird can retrieve the configuration automatically.

Automatic client configuration for Microsoft clients

Microsoft uses its own standard for automatic configuration. An SRV record is required for the autodiscover function of email programs (e.g. Outlook):

\_autodiscover.\_tcp IN SRV 0 0 443 auto.mailbox.org.

Step-by-step instructions:

1. In the DNS console, select the desired domain (zone).
2. Click Add Record and select SRV as record type.
3. Enter _autodiscover._tcp as the hostname.
4. Configure the following values:
   • Priority: 0
   • Weight: 0
   • Port: 443
   • Target: auto.mailbox.org.
   Note for Netcup

   With Netcup, you cannot configure the settings for weight/priority and port individually.

5. Save the SRV record.

Microsoft Outlook typically uses the autodiscover subdomain, which is why the hostname in the DNS records differs from that of Thunderbird.

Note

Depending on the provider, DNS changes can take up to 24 hours to become active.

Microsoft Outlook – version differences

Not all versions of Microsoft Outlook support DNS-based auto-configuration equally.

Outlook Version	Automatic Configuration	Notes
Outlook 2013	Yes	Fully supported
Outlook 2016 (without Microsoft account)	Limited	Works if no M365 account is set up
Outlook 2019 / Microsoft 365	No	Microsoft defaults to Exchange Online and ignores custom DNS records

Hosting the XML file on your own server

Alternatively, you can host an XML file on your own web server containing the mailbox email server data.

This XML file must follow a defined syntax, which is explained in detail in the Mozilla Wiki. You can specify the domain, incoming and outgoing mail servers including ports, and even define encryption methods and authentication mechanisms.

mailbox provides you with a ready-made file with all required settings, which you can download here:
https://mailbox.org/mail/config-v1.1.xml

If you want to use this configuration for your own domain, you only need to adapt the three header fields:

• domain
• displayName
• displayShortName

Then save the file in the appropriate location on your web server.