Frequently asked questions

Informational

Where to ask questions?

First, please read this FAQ to check if your question is listed here. Simple questions best fit in our Matrix room. For more complex questions, you can always open a new issue on GitHub. We actively monitor the issues list.

My installation is broken!

We’re sorry to hear that. Please check for common mistakes and troubleshooting advice in the Technical issues section of this page.

I think I found a bug!

If you did not manage to solve the issue using this FAQ and there is not any open issues describing the same problem, you can continue to open a new issue on GitHub.

I want a new feature or enhancement!

Great! We are always open for suggestions. We currently maintain two tags:

• Enhancement issues: Typically used for optimization of features in the project.

• Feature request issues: For implementing new functionality, plugins and applications.

Please check if your idea (or something similar) is already mentioned there. If there is one open, you can choose to vote with a thumbs up, so we can estimate the popular demand. Please refrain from writing comments like “me too” as it clobbers the actual discussion.

If you can’t find anything similar, you can open a new issue. Please also share (where applicable):

• Use case: how does this improve the project?

• Any research done on the subject. Perhaps some links to upstream website, reference implementations etc.

Why does my feature/bug take so long to solve?

You should be aware that creating, maintaining and expanding a mail server distribution requires a lot of effort. Mail servers are highly exposed to hacking attempts, open relay scanners, spam and malware distributors etc. We need to work in a safe way and have to prevent pushing out something quickly.

TODO: Move the next section into the contributors part of docs We currently maintain a strict work flow:

1. Someone writes a solution and sends a pull request;

2. We use Github actions for some very basic building and testing;

3. The pull request needs to be code-reviewed and tested by at least two members from the contributors team.

Please consider that this project is mostly developed in people their free time. We thank you for your understanding and patience.

I would like to donate (for a feature)

We maintain a Communtity Bridge project through which you can donate. This budget will be used to pay for development of features, mentorship and hopefully future events. Contributing companies or individuals can be paid from this budget to support their development efforts.

We are also looking into GitHub’s integrated sponorship program for individual contributors. Once those become available, we will add them to the project.

Please click the button on top of our GitHub Page for current possibilities.

Deployment related

What is the difference between DOMAIN and HOSTNAMES?

Similar questions:

• Changing domain doesn’t work

• Do I need a certificate for DOMAIN?

DOMAIN is the main mail domain. Aka, server identification for outgoing mail. DMARC reports point to POSTMASTER @ DOMAIN. These are really the only things it is used for. You don’t need a cert for DOMAIN, as it is a mail domain only and not used as host in any sense. However, it is usual that DOMAIN gets setup as one of the many mail domains. None of the mail domains ever need a certificate. TLS certificates work on host connection level only.

HOSTNAMES however, can be used to connect to the server. All host names supplied in this variable will need a certificate. When TLS_FLAVOR=letsencrypt is set, a certificate is requested automatically for all those domains.

So when you have something like this:

DOMAIN=example.com
POSTMASTER=me
HOSTNAMES=mail.example.com,mail.foo.com,bar.com
TLS_FLAVOR=letsencrypt

• You’ll end up with a DMARC address to me@example.com.

• Server identifies itself as the SMTP server of @example.com when sending mail. Make sure your reverse DNS hostname is part of that domain!

• Your server will have certificates for the 3 hostnames. You will need to create A and AAAA records for those names, pointing to the IP addresses of your server.

• The admin interface generates MX and SPF examples which point to the first entry of HOSTNAMES but these are only examples. You can modify them to use any other HOSTNAMES entry.

Your mail service will be reachable for IMAP, POP3, SMTP and Webmail at the addresses:

• mail.example.com

• mail.foo.com

• bar.com

Note

In this case example.com is not reachable as a host and will not have a certificate. It can be used as a mail domain if MX is setup to point to one of the HOSTNAMES. However, it is possible to include example.com in HOSTNAMES.

Issue reference: 742, 747.

How to make IPv6 work?

Docker currently does not expose the IPv6 ports properly, as it does not interface with ip6tables. Lets start with quoting everything that’s wrong:

Unfortunately, initially Docker was not created with IPv6 in mind. It was added later and, while it has come a long way, is still not as usable as one would want. Much discussion is still going on as to how IPv6 should be used in a containerized world; See the various GitHub issues linked below:

• Giving each container a publicly routable address means all ports (even unexposed / unpublished ports) are suddenly reachable by everyone, if no additional filtering is done (docker/docker#21614)

• By default, each container gets a random IPv6, making it impossible to do properly do DNS; the alternative is to assign a specific IPv6 address to each container, still an administrative hassle (docker/docker#13481)

• Published ports won’t work on IPv6, unless you have the userland proxy enabled (which, for now, is enabled by default in Docker)

• The userland proxy, however, seems to be on its way out (docker/docker#14856) and has various issues, like:

  • It can use a lot of RAM (docker/docker#11185)

  • Source IP addresses are rewritten, making it completely unusable for many purposes, e.g. mail servers (docker/docker#17666), (docker/libnetwork#1099).

—Robbert Klarenbeek (docker-ipv6nat author)

Okay, but I still want to use IPv6! Can I just use the installers IPv6 checkbox? NO, YOU SHOULD NOT DO THAT! Why you ask? Mailu has its own trusted IPv4 network, every container inside this network can use e.g. the SMTP container without further authentication. If you enabled IPv6 inside the setup assistant (and fixed the ports to also be exposed on IPv6) Docker will still rewrite any incoming IPv6 requests to an IPv4 address, which is located inside the trusted network. Therefore any incoming connection to the SMTP container will bypass the authentication stage by the front container regardless of your settings and causes an Open Relay. And you really don’t want this!

So, how to make it work? Well, by using docker-ipv6nat! This nifty container will set up ip6tables, just as Docker would do for IPv4. We know that nat-ing is not advised in IPv6, however exposing all containers to public network neither. The choice is ultimately yous.

Mailu setup utility generates a safe IPv6 ULA subnet by default. So when you run the following command, Mailu will start to function on IPv6:

docker run -d --restart=always -v /var/run/docker.sock:/var/run/docker.sock:ro --privileged --net=host robbertkl/ipv6nat

How does Mailu scale up?

Recent works allow Mailu to be deployed in Docker Swarm and Kubernetes. This means it can be scaled horizontally. For more information, refer to Kubernetes setup or the Docker swarm howto.

Issue reference: 165, 520.

How to achieve HA / failover?

The mailboxes and databases for Mailu are kept on the host filesystem under $ROOT/. For making the storage highly available, all sorts of techniques can be used:

• Local raid-1

• btrfs in raid configuration

• Distributed network filesystems such as GlusterFS or CEPH

Note that no storage HA solution can protect against incidental deletes or file corruptions. Therefore it is advised to create backups on a regular base!

A backup MX can be configured as failover. For this you need a separate server running Mailu. On that server, your domains will need to be setup as “Relayed domains”, pointing to you main server. MX records for the mail domains with a higher priority number will have to point to this server. Please be aware that a backup MX can act as a spam magnet.

For service HA, please see: How does Mailu scale up?

Issue reference: 177, 591.

Does Mailu run on Rancher?

There is a rancher catalog for Mailu in the Mailu/Rancher repository. The user group for Rancher is small, so we cannot promise any support on this when you’re heading into trouble. See the repository README for more details.

Issue reference: 125.

Can I run Mailu without host iptables?

When disabling iptables in docker, its forwarding proxy process takes over. This creates the situation that every incoming connection on port 25 seems to come from the local network (docker’s 172.17.x.x) and is accepted. This causes an open relay!

For that reason we do not support deployment on Docker hosts without iptables.

Issue reference: 332.

How can I override settings?

Postfix, Dovecot, Nginx and Rspamd support overriding configuration files. Override files belong in $ROOT/overrides. Please refer to the official documentation of those programs for the correct syntax. The following file names will be taken as override configuration:

• Postfix :

  • main.cf as $ROOT/overrides/postfix/postfix.cf

  • master.cf as $ROOT/overrides/postfix/postfix.master

  • All $ROOT/overrides/postfix/*.map files

  • For both postfix.cf and postfix.master, you need to put one configuration per line, as they are fed line-by-line to postfix.

  • logrotate.conf as $ROOT/overrides/postfix/logrotate.conf - Replaces the logrotate.conf file used for rotating POSTFIX_LOG_FILE.

• Dovecot - dovecot.conf in dovecot sub-directory;

• Nginx - All *.conf files in the nginx sub-directory;

• Rspamd - All files in the rspamd sub-directory.

• Roundcube - All *.inc files in the roundcube sub directory.

To override the root location (/) in Nginx WEBROOT_REDIRECT needs to be set to none in the env file (see web settings).

Issue reference: 206, 1368.

I want to integrate Nextcloud 15 (and newer) with Mailu

1. Enable External user support from Nextcloud Apps interface

2. Configure additional user backends in Nextcloud’s configuration config/config.php using the following syntax if you use at least Nextcloud 15.

<?php

/** Use this for Nextcloud 15 and newer **/
'user_backends' => array(
    array(
        'class' => 'OC_User_IMAP',
        'arguments' => array(
          '127.0.0.1', 993, 'ssl', 'example.com', true, false
      ),
    ),
),

If a domain name (e.g. example.com) is specified, then this makes sure that only users from this domain will be allowed to login. After successfull login the domain part will be striped and the rest used as username in Nextcloud. e.g. ‘username@example.com’ will be ‘username’ in Nextcloud. Disable this behaviour by changing true (the fifth parameter) to false.

Issue reference: 575.

I want to integrate Nextcloud 14 (and older) with Mailu

1. Install dependencies required to authenticate users via imap in Nextcloud

apt-get update \
 && apt-get install -y libc-client-dev libkrb5-dev \
 && rm -rf /var/lib/apt/lists/* \
 && docker-php-ext-configure imap --with-kerberos --with-imap-ssl \
 && docker-php-ext-install imap

2. Enable External user support from Nextcloud Apps interface

3. Configure additional user backends in Nextcloud’s configuration config/config.php using the following syntax for Nextcloud 14 (and below):

<?php

/** Use this for Nextcloud 14 and older **/
'user_backends' => array(
    array(
        'class' => 'OC_User_IMAP',
        'arguments' => array(
            '{imap.example.com:993/imap/ssl}', 'example.com'
        ),
    ),
),

If a domain name (e.g. example.com) is specified, then this makes sure that only users from this domain will be allowed to login. After successfull login the domain part will be striped and the rest used as username in Nextcloud. e.g. ‘username@example.com’ will be ‘username’ in Nextcloud.

Issue reference: 575.

How do I use webdav (radicale)?

For first time set up, the user must access radicale via the url https://mail.example.com/webdav/.web and then

1. Log in using the user’s full email address and password.

2. Click ‘Create new addressbook or calendar’

3. Follow instructions for creating an addressbook (for contact management) and calendar.

Subsequently to use webdav (radicale), you can configure your carddav/caldav client to use the following url:

https://mail.example.com/webdav/user@example.com

As username you must provide the complete email address (user@example.com).

As password you must provide the password of the email address.

The user must be an existing Mailu user.

issue reference: 1591.

How do I setup a MTA-STS policy?

Mailu can serve an MTA-STS policy; To configure it you will need to:

1. add mta-sts.example.com to the HOSTNAMES configuration variable (and ensure that a valid SSL certificate is available for it; this may mean restarting your smtp container)

2. configure an override with the policy itself; for example, your overrides/nginx/mta-sts.conf could read:

location ^~ /.well-known/mta-sts.txt {
return 200 "version: STSv1
mode: enforce
max_age: 1296000
mx: mailu.example.com\r\n";
}

3. setup the appropriate DNS/CNAME record (mta-sts.example.com -> mailu.example.com) and DNS/TXT record (_mta-sts.example.com -> v=STSv1; id=1) paying attention to the TTL as this is used by MTA-STS.

issue reference: 1798.

How do I setup client autoconfiguration?

Mailu can serve an XML file for autoconfiguration; To configure it you will need to:

1. add autoconfig.example.com to the HOSTNAMES configuration variable (and ensure that a valid SSL certificate is available for it; this may mean restarting your smtp container)

2. configure an override with the policy itself; for example, your overrides/nginx/autoconfiguration.conf could read:

location ^~ /mail/config-v1.1.xml {
return 200 "<?xml version=\"1.0\"?>
<clientConfig version=\"1.1\">
<emailProvider id=\"%EMAILDOMAIN%\">
<domain>%EMAILDOMAIN%</domain>

<displayName>Email</displayName>
<displayShortName>Email</displayShortName>

<incomingServer type=\"imap\">
<hostname>mailu.example.com</hostname>
<port>993</port>
<socketType>SSL</socketType>
<username>%EMAILADDRESS%</username>
<authentication>password-cleartext</authentication>
</incomingServer>

<outgoingServer type=\"smtp\">
<hostname>mailu.example.com</hostname>
<port>465</port>
<socketType>SSL</socketType>
<username>%EMAILADDRESS%</username>
<authentication>password-cleartext</authentication>
<addThisServer>true</addThisServer>
<useGlobalPreferredServer>true</useGlobalPreferredServer>
</outgoingServer>

<documentation url=\"https://mailu.example.com/admin/ui/client\">
<descr lang=\"en\">Configure your email client</descr>
</documentation>
</emailProvider>
</clientConfig>\r\n";
}

3. setup the appropriate DNS/CNAME record (autoconfig.example.com -> mailu.example.com).

issue reference: 224.

Technical issues

In this section we are trying to cover the most common problems our users are having. If your issue is not listed here, please consult issues with the troubleshooting tag.

Changes in .env don’t propagate

Variables are sent to the containers at creation time. This means you need to take the project down and up again. A container restart is not sufficient.

docker-compose down && \
docker-compose up -d

Issue reference: 615.

SMTP Banner from overrides/postfix.cf is ignored

Any mail related connection is proxied by nginx. Therefore the SMTP Banner is also set by nginx. Overwriting in overrides/postfix.cf does not apply.

Issue reference: 1368.

My emails are getting defered, what can I do?

Emails are asynchronous and it’s not abnormal for them to be defered sometimes. That being said, Mailu enforces secure connections where possible using DANE and MTA-STS, both of which have the potential to delay indefinitely delivery if something is misconfigured.

If delivery to a specific domain fails because their DANE records are invalid or their TLS configuration inadequate (expired certificate, …), you can assist delivery by downgrading the security level for that domain by creating an override at overrides/postfix/tls_policy.map as follow:

domain.example.com   may
domain.example.org   encrypt

The syntax and options are as described in postfix’s documentation. Re-creating the smtp container will be required for changes to take effect.

403 - Access Denied Errors

While this may be due to several issues, check to make sure your DOMAIN= entry is the first entry in your HOSTNAMES=.

TLS certificate issues

When there are issues with the TLS/SSL certificates, Mailu denies service on secure ports. This is a security precaution. Symptoms are:

• 403 browser errors;

These issues are typically caused by four scenarios:

1. TLS_FLAVOR=notls in .env;

2. Certificates expired;

3. When TLS_FLAVOR=letsencrypt, it might be that the certbot script is not capable of obtaining the certificates for your domain. See letsencrypt issues

4. When TLS_FLAVOR=certs, certificates are supposed to be copied to /mailu/certs. Using an external letsencrypt program, it tends to happen people copy the whole letsencrypt/live directory containing symlinks. Symlinks do not resolve inside the container and therefore it breaks the TLS implementation.

letsencrypt issues

In order to determine the exact problem on TLS / Let’s encrypt issues, it might be helpful to check the logs.

docker-compose logs front | less -R
docker-compose exec front less /var/log/letsencrypt/letsencrypt.log

Common problems:

• Port 80 not reachable from outside.

• Faulty DNS records: make sure that all HOSTNAMES have A (IPv4) and AAAA (IPv6) records, pointing the the BIND_ADDRESS4 and BIND_ADDRESS6.

• DNS cache not yet expired. It might be that old / faulty DNS records are stuck in a cache en-route to letsencrypt’s server. The time this takes is set by the TTL field in the records. You’ll have to wait at least this time after changing the DNS entries. Don’t keep trying, as you might hit rate-limits.

Copying certificates

As mentioned above, care must be taken not to copy symlinks to the /mailu/certs location.

The wrong way!:

cp -r /etc/letsencrypt/live/domain.com /mailu/certs

The right way!:

mkdir -p /mailu/certs
cp /etc/letsencrypt/live/domain.com/privkey.pem /mailu/certs/key.pem
cp /etc/letsencrypt/live/domain.com/fullchain.pem /mailu/certs/cert.pem

See also Managing of external Let’s encrypt certificates.

Issue reference: 426, 615.

How do I activate DKIM and DMARC?

Go into the Domain Panel and choose the Domain you want to enable DKIM for. Click the first icon on the left side (domain details). Now click on the top right on the “Regenerate Keys” Button. This will generate the DKIM and DMARC entries for you.

Issue reference: 102.

Do you support Fail2Ban?

Fail2Ban is not included in Mailu. Fail2Ban needs to modify the host’s IP tables in order to ban the addresses. We consider such a program should be run on the host system and not inside a container. The front container does use authentication rate limiting to slow down brute force attacks. The same applies to login attempts via the single sign on page.

We do provide a possibility to export the logs from the front service and Admin service to the host. The front container logs failed logon attempts on SMTP, IMAP and POP3. The Admin``container logs failed logon attempt on the single sign on page. For this you need to set ``LOG_DRIVER=journald or syslog, depending on the log manager of the host. You will need to setup the proper Regex in the Fail2Ban configuration. Below an example how to do so.

If you use a reverse proxy in front of Mailu, it is vital to set the environment variables REAL_IP_HEADER and REAL_IP_FROM. Without these environment variables, Mailu will not trust the remote client IP passed on by the reverse proxy and as a result your reverse proxy will be banned. See the [configuration reference for more information.

Assuming you have a working Fail2Ban installation on the host running your Docker containers, follow these steps:

1. In the mailu docker-compose set the logging driver of the front container to journald; and set the tag to mailu-front

logging:
  driver: journald
  options:
    tag: mailu-front

2. Add the /etc/fail2ban/filter.d/bad-auth.conf

# Fail2Ban configuration file
[Definition]
failregex = .* client login failed: .+ client:\ <HOST>
ignoreregex =
journalmatch = CONTAINER_TAG=mailu-front

3. Add the /etc/fail2ban/jail.d/bad-auth.conf

[bad-auth]
enabled = true
backend = systemd
filter = bad-auth
bantime = 604800
findtime = 300
maxretry = 10
action = docker-action

The above will block flagged IPs for a week, you can of course change it to you needs.

4. In the mailu docker-compose set the logging driver of the Admin container to journald; and set the tag to mailu-admin

logging:
  driver: journald
  options:
    tag: mailu-admin

5. Add the /etc/fail2ban/filter.d/bad-auth-sso.conf

# Fail2Ban configuration file
[Definition]
failregex = .* Login failed for .+ from <HOST>.
ignoreregex =
journalmatch = CONTAINER_TAG=mailu-admin

6. Add the /etc/fail2ban/jail.d/bad-auth-sso.conf

[bad-auth-sso]
enabled = true
backend = systemd
filter = bad-auth-sso
bantime = 604800
findtime = 300
maxretry = 10
action = docker-action

The above will block flagged IPs for a week, you can of course change it to you needs.

7. Add the /etc/fail2ban/action.d/docker-action.conf

[Definition]

actionstart = iptables -N f2b-bad-auth
              iptables -A f2b-bad-auth -j RETURN
              iptables -I DOCKER-USER -p tcp -m multiport --dports 1:1024 -j f2b-bad-auth

actionstop = iptables -D DOCKER-USER -p tcp -m multiport --dports 1:1024 -j f2b-bad-auth
             iptables -F f2b-bad-auth
             iptables -X f2b-bad-auth

actioncheck = iptables -n -L DOCKER-USER | grep -q 'f2b-bad-auth[ \t]'

actionban = iptables -I f2b-bad-auth 1 -s <ip> -j DROP

actionunban = iptables -D f2b-bad-auth -s <ip> -j DROP

Using DOCKER-USER chain ensures that the blocked IPs are processed in the correct order with Docker. See more in: https://docs.docker.com/network/iptables/

8. Configure and restart the Fail2Ban service

Make sure Fail2Ban is started after the Docker service by adding a partial override which appends this to the existing configuration.

sudo systemctl edit fail2ban

Add the override and save the file.

[Unit]
After=docker.service

Restart the Fail2Ban service.

sudo systemctl restart fail2ban

Issue reference: 85, 116, 171, 584, 592, 1727.

Users can’t change their password from webmail

All users have the abilty to login to the admin interface. Non-admin users have only restricted funtionality such as changing their password and the spam filter weight settings.

Issue reference: 503.

rspamd: DNS query blocked on multi.uribl.com

This usually relates to the DNS server you are using. Most of the public servers block this query or there is a rate limit. In order to solve this, you most probably are better off using a root DNS resolver, such as unbound. This can be done in multiple ways:

• Use the Mailu/unbound container. This is an optional include when generating the docker-compose.yml file with the setup utility.

• Setup unbound on the host and make sure the host’s /etc/resolve.conf points to local host. Docker will then forward all external DNS requests to the local server.

• Set up an external DNS server with root resolving capabilities.

In any case, using a dedicated DNS server will improve the performance of your mail server.

Issue reference: 206, 554, 681.

Can I learn ham/spam messages from an already existing mailbox?

Mailu is supporting automatic spam learning for messages moved to the Junk mailbox. Any email moved from the Junk Folder will learnt as ham.

If you already have an existing mailbox and want Mailu to learn them all as ham messages, you might run rspamc from within the dovecot container:

rspamc -h antispam:11334 -P mailu -f 13 fuzzy_add /mail/user\@example.com/.Ham_Learn/cur/
rspamc -h antispam:11334 -P mailu learn_ham /mail/user\@example.com/.Ham_Learn/cur/

This should learn every file located in the Ham_Learn folder from user@example.com

Likewise, to lean all messages within the folder Spam_Learn as spam messages :

rspamc -h antispam:11334 -P mailu -f 11 fuzzy_add /mail/user\@example.com/.Spam_Learn/cur/
rspamc -h antispam:11334 -P mailu learn_spam /mail/user\@example.com/.Spam_Learn/cur/

Issue reference: 1438.

Is there a way to support more (older) ciphers?

You will need to rewrite the tls.conf template of the front container in core/nginx.

You can set the protocols as follow:

ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
ssl_ciphers <list of ciphers>;

After applying the change, you will need to rebuild the image and use it in your deployment.

We strongly advice against downgrading the TLS version and ciphers, please upgrade your client instead! We will not support a more standard way of setting this up.

Issue reference: 363, 698.

Why does Compose complain about the yaml syntax

In many cases, Docker Compose will complain about the yaml syntax because it is too old. It is especially true if you installed Docker Compose as part of your GNU/Linux distribution package system.

Unless your distribution has proper up-to-date packages for Compose, we strongly advise that you install it either:

• from the Docker-CE repositories along with Docker CE itself,

• from PyPI using pip install docker-compose or

• from Github by downloading it directly.

Detailed instructions can be found at https://docs.docker.com/compose/install/

Issue reference: 853.

Why are still spam mails being discarded?

Disabling antispam in the user settings actually disables automatic classification of messages as spam and stops moving them to the junk folder. It does not stop spam scanning and filtering.

Therefore, messages still get discarded if their spam score is so high that the antispam finds them unfit for distribution. Also, the antispam headers are still present in the message, so that mail clients can display it and classify based on it.

Issue reference: 897.

Why is SPF failing while properly setup?

Very often, SPF failure is related to Mailu sending emails with a different IP address than the one configured in the env file.

This is mostly due to using a separate IP address for Mailu and still having masquerading nat setup for Docker, which results in a different outbound IP address. You can simply check the email headers on the receiving side to confirm this.

If you wish to explicitely nat Mailu outbound traffic, it is usually easy to source-nat outgoing SMTP traffic using iptables :

` iptables -t nat -A POSTROUTING -o eth0 -p tcp --dport 25 -j SNAT --to <your mx ip> `

Issue reference: 1090.

A user gets Sender address rejected: Access denied. Please check the message recipient […] and try again even though the sender is legitimate?

First, check if you are really sure the user is a legitimate sender, i.e. the registered user is authenticated successfully and own either the account or alias he/she is trying to send from. If you are really sure this is correct, then the user might try to errornously send via port 25 insteadof the designated SMTP client-ports. Port 25 is meant for server-to-server delivery, while users should use port 587 or 465.

The admin container won’t start and its log says Critical: your DNS resolver isn't doing DNSSEC validation

Since v1.9, Mailu requires a validating DNSSEC enabled DNS resolver. To check whether your DNS resolver (and its upstream) fits the requirements you can use the following command and see whether the AD flag is present in the reply:

dig @<ip> +adflag example.org A

We recommend that you run your own DNS resolver (enable unbound and update your docker-compose.yml when you update from older versions) instead of relying on publicly available ones. It’s better security-wise (you don’t have to trust them) and RBLs used by rspamd are known to rate-limit per source-ip address.

We have seen a fair amount of support requests related to the following:

• dnsmasq won’t forward DNSSEC results unless instructed to do so. If you are running openwrt or pi-hole, you do need to enable DNSSEC.

• coredns has a bug that we have now worked around