- Using private DNS servers allows you to filter out ad domains, trackers, and malware before the connection is established from your mobile device.
- Combining DNS filtering with blocking external images in email drastically reduces the effectiveness of tracking pixels.
- Privacy-focused services (Proton Mail, NextDNS, Pi-hole, email aliases) add extra layers of protection without changing how you use your mobile phone.
- The proposed measures are free, reversible, and improve privacy and security without significantly affecting device performance.
If you think that when you open your email on your phone you're just reading messages, you're missing an important part of the picture. In the background, many emails include invisible tracking pixels and connections to tracking domains that send information to the sender without you doing anything. And the same thing happens with many of the apps you use daily.
The good news is that you can cut off much of that silent spying by changing a single setting on your phone and combining it with a few simple tricks. The most interesting thing is that You don't need to be a network expert or install complicated toolsWith a well-chosen DNS, a couple of adjustments in your email client, and some common sense (for example, activate a near-total privacy mode), you can greatly reduce the trace you leave.
What are hidden trackers in emails and apps?
When you open an email or an application, it's not just the content you see that loads. In many cases, other processes are also executed. third-party modules dedicated to analytics, advertising, and profiling from the user. These modules connect to external servers to send data about what you do.
In the case of email, the star trick is the so-called tracking pixelA tiny image (usually 1x1 pixel) embedded in the message. It's invisible to you, but when loaded from the sender's server, it tells them that you've opened the email, from which device, your IP address, the date and time, the operating system, the browser, and sometimes even if you've clicked on certain links.
Something similar happens with apps. Many popular apps integrate libraries of advertising, analytics or synchronization companies that monitor the time you spend on each screen, which buttons you press, which links you open, which other apps you use, and can even infer your approximate location even if you haven't directly allowed it (how can they hack your mobile).
All this tracking traffic leaves your phone silently. You don't see any notifications, no alerts appear on the screen, and sometimes there isn't even a clear consent banner. The goal is build a profile that is as detailed as possible about your habits to better segment you in marketing campaigns or, directly, to sell that data to third parties.
The role of DNS in tracking: the Internet phone book
To understand how to sever many of these connections, it's essential to understand what DNS is. The Domain Name System works like an internet phone bookWhen you type an address (for example, that of your favorite website or that of an email server), your mobile phone asks a DNS server which IP address corresponds to that domain, and only then is the connection established.
By default, the DNS you use is usually that of your internet service provider or large companies like Google. This means that entity can see Which domains is your mobile trying to connect to?: what websites you visit, what services you use, and what applications communicate in the background, even if the content is encrypted by HTTPS.
Although the DNS doesn't see the exact content of what you're doing, the list of domains is more than enough to deduce your interests, your daily routine, the type of services you use And often, your approximate location. That's precisely where the use of private, privacy-focused DNS and tracker blocking comes into play.
Furthermore, the applications themselves don't just communicate with one server. An email app, for example, can connect to image servers, analytics servers, advertising servers, open tracking servers, and so on. Each of these connections first goes through the DNS, so control which domains are resolved and which are not It's a very effective way to prune trackers without changing how you use your mobile phone.
Options to block trackers and ads on mobile
In practice, there are several strategies to stop ads and trackers on your mobile device. Some focus on blocking all network traffic, others only browser traffic, and others involve... use specialized DNS serversEach one has its advantages and disadvantages.
1. Local VPN-based blocking applications
One of the most popular solutions is to install applications such as AdGuard, Blokada, AdAway or RethinkDNSThese apps create a kind of "local VPN" on the device: they redirect all your traffic through a profile that filters out ad domains, trackers, and malware before the connection is completed.
This approach has several strengths. For one thing, it allows Block ads and tracking in virtually all appsnot only in the browser. Furthermore, many of these tools are open source (such as RethinkDNS or AdAway), which provides greater transparency about their internal workings.
However, it's not all advantages. Maintaining an active local VPN involves a additional battery and resource consumptionBecause the app needs to be running constantly to analyze connections. Also, if you want to use your own commercial VPN (for example, with WireGuard), there may be conflicts: some apps don't allow combining both, or require more advanced configurations.
2. Blocking on the local network with Pi-hole
If you're concerned about the privacy of your entire home or office, a very powerful option is to install Pi-hole on a Raspberry Pi or other always-on devicePi-hole acts as a DNS server for the entire local network and blocks ads, trackers, and malicious domains before they reach your devices.
The idea is simple: you configure your router or your devices to use the Raspberry Pi's IP address as the DNS server. From there, any mobile phone, TV, console or laptop Being on that network benefits from filtering without needing to install anything on each device.
Among its advantages, Pi-hole offers real-time statistics on DNS requests, allowing you to see which domains are trying to contact your deviceshow many requests are blocked and from which device. You can even create specific rules for a particular device, giving you quite a bit of fine-grained control.
The downside is that it requires a bit of skill: you need some small hardware (like a Raspberry Pi), to install an operating system (for example, Ubuntu Server), to follow the Pi-hole wizard, and touch the router or device settingsIt's not crazy, but it's not "plug and play" either, so not everyone is willing to take that step.
3. Custom DNS: the simplest option for most
For the vast majority of users, the most practical thing is Change your mobile's private DNS to one specialized in privacy and blocking.It's a quick adjustment, uses almost no battery, works at the system level, and is reversible at any time.
On Android (from certain versions onwards) you can go to Settings → Network & Internet → Private DNS. There you select “Private DNS provider hostname” and enter the host you want to use. From that moment on, All device connections pass through that encrypted DNS.This reduces tracking by your carrier and allows you to activate advanced filters if the provider offers them.
Recommended DNS servers to block trackers and malware
Not all DNS servers are created equal. Some focus on speed, others on security, and a few prioritize [the following]. privacy and blocking annoying domainsThese are some of the most interesting ones to use from your mobile phone.
AdGuard DNS
AdGuard DNS offers servers specifically designed for Remove ads, trackers, and malicious domainsIt's a very convenient option if you want something that works "out of the box" without having to mess with too many lists.
A typical Android configuration involves setting the host as the private DNS. dns.adguard.com or its ad-blocking variant. With that, in many cases you'll see a very noticeable reduction (close to 99% in some scenarios) in banners and trackers while browsing and using apps.
AdGuard also offers a web panel with statistics and advanced options if you register, allowing See which domains are being blocked and adjust the filtering level.It's a quick way to gain privacy without any hassle.
Quad9
Another highly valued DNS is Quad9 (dns.quad9.net)Primarily focused on security, its main function is to prevent your device from connecting to domains categorized as malicious (phishing, malware, botnets, etc.), thanks to lists maintained by cybersecurity organizations.
Although Quad9 is not as focused on advertising as AdGuard, it does contribute to block part of the tracking associated with dangerous and suspicious domainsIt's a good choice if you prioritize avoiding attacks and fraudulent websites, and want improved privacy without messing with too many settings.
Google DNS
The famous dns. google It's a fast and very stable public DNS, widely used around the world. However, in terms of pure privacy, it's not the best option: it belongs to one of the largest advertising companies on the planet, and although it has a fairly well-documented data usage policy, It is not specifically designed to minimize tracking.but to provide a reliable service.
If you're only looking to improve speed and stability compared to your ISP's DNS, it can be a good alternative, but It's not the ideal option if your absolute priority is privacy. and blocking trackers.
Mullvad DNS
Less well known to the general public, but highly valued by those concerned about their digital footprint, is the DNS of Mullvad (all.dns.mullvad.net, adblock.dns.mullvad.net)It is developed by the same team behind Mullvad VPN, which boasts a strict no-logs policy.
Their DNS servers offer different profiles: one general, another with ad blocker and trackers...and even family-oriented versions (with adult content filters). It's a very solid alternative if you want to combine speed, privacy, and blocking without relying on tech giants.
ControlD, NextDNS and other advanced providers
In addition to the above, there are services such as ControlD (for example, family.freedns.controld.com) o NextDNSwhich allow for a very high level of customization. You can choose blocklists for ads, trackers, social media, domains of major tech companies, adult content, online games, etc.
In the specific case of NextDNS, after registering you create your own configuration and activate different filters. In the panel you can Block tracking domains from Amazon, Apple, Google, and many other companiesas well as viewing real-time logs of what is being blocked on your device.
To use it on Android, copy the "DNS over TLS/QUIC" URL generated by NextDNS and paste it into the hostname field of your private DNS. The drawback is that their free plan is usually limited to a few 300.000 monthly consultationsalthough it is usually sufficient for a single device.
How to change private DNS on Android step by step
Changing the private DNS on Android is one of those settings that They make a difference and are done in a minuteThe exact path may vary depending on the Android brand and version, but the general process is very similar.
In general terms, the steps are:
- Open the Settings of the mobile.
- Enter the section Network and Internet or similar (sometimes it appears as “Connections”).
- Look for the section Private DNS or “Private DNS/private DNS”.
- Select the option “Private DNS provider hostname".
- Enter the host of the service you want to use (for example, dns.adguard.com, dns.quad9.net, the NextDNS URL, etc.).
- Save the changes and make sure the option appears as “Enabled”.
From that moment on, your phone will stop using the carrier's DNS and will resolve all addresses through your chosen provider. This doesn't encrypt all your traffic (for that you would still need a VPN), but it does This prevents your ISP from easily seeing which domains you connect to. And, above all, it allows you to apply automatic filters against trackers and ads.
The advantage is that it is a measure free, reversible and does not affect normal mobile phone useIf you ever have problems with a website or app, simply disable private DNS or try a different provider. It's hard to find another privacy improvement this simple with such an immediate impact. For more details on the process, see [link to relevant documentation]. How to configure private DNS on Android.
Targeted blocking of trackers in emails
So far we've focused on the network layer, but emails have their own tracking tricks, and it's worth targeting them from within the email client itself. After all, tracking pixels work primarily... as remote content loaded via HTTP(S)And there you have several levers in your favor.
Disable automatic image uploading
The quickest and most effective way to cut tracking pixels is prevent external images from being automatically loadedSince many trackers disguise themselves as a tiny image hosted on an external server, if they are not downloaded, the sender does not receive the opening notification.
In Gmail, for example, you can go to Settings → Images and select the option to “Ask before showing external images”With that, emails will not load images by default, and they will only be displayed when you authorize it.
In Apple Mail (on both iPhone and Mac), under Settings → Mail, you have an option to disable “Upload remote contentBy doing so, you ensure that no hidden pixels in external images are downloaded without your permission.
In Outlook the path is similar: from Settings → Accounts you can activate “Block external images”This way, the client will first see the "bare" email and will only download the images that you choose.
The only downside is that some emails (especially newsletters and promotions) may look a little less attractive or empty until you approve the images. But in return You stop giving away information about your openings without even knowing itwhich for many people more than makes up for it.
Use privacy-focused email services
If you're genuinely worried about being tracked via email, it might be worth considering switching providers. Platforms like Proton Mail, Tutanota or StartMail They are designed with privacy as a priority, not as an add-on.
These services typically block tracking pixels by default, filter common trackers, and also offer end-to-end encryptionso that only you and the recipient can read the message content. They also typically operate from countries with strict privacy laws, which adds a legal layer of protection.
Another plus is that many of these providers implement Better anti-spam filters and they don't monetize your data for advertising.This reduces the amount of spam and aggressive marketing practices. Although switching platforms might seem daunting at first, most of them have polished mobile apps and websites that make the transition easy.
Browser extensions to block trackers in webmail
If you primarily read your email through a web browser (for example, Gmail in Chrome or Firefox), you can add an extra layer of protection with dedicated extensions. There are add-ons such as Email Privacy Protector that analyze the content of emails and detect if they include tracking pixels.
These extensions usually automatically block suspicious items and show you a warning icon next to the message when tracking is detected. In some cases, they even prevent the sender from knowing you've opened the email, because the pixel never actually downloads.
However, it's important to only install extensions from trusted sources, such as the official Chrome or Firefox stores. A malicious extension can create a bigger problem than the one it's trying to solve, so It's better to err on the side of caution than to grant access permissions to your email..
Email alias to hide your real address
Another very useful tactic, especially for website and newsletter sign-ups, is to use email aliasesServices like SimpleLogin, Proton Pass, or AnonAddy generate disposable addresses that redirect messages to your real account, but they can filter trackers along the way.
The beauty of this strategy is that if a specific alias starts receiving spam or highly stalking emails, you know where the leak is coming from and You can disable that alias without touching your main address.It's like having several "mailbox addresses" for different uses: online shopping, dubious registrations, forums, etc.
Many modern providers also integrate alias creation directly into their platform, simplifying management. It's advisable to have more than one address: one for personal and trusted use, another for registrations that might generate spam, and temporary aliases for... services that don't inspire much confidence.
Other layers of protection: browser and home network
All of the above is complemented very well by browser-level blockers such as uBlock OriginAnd, if you're looking for anonymity, Using Tor on AndroidThis extension, available for Chrome, Firefox, and other browsers, will filter ads, trackers, and malicious domains while you browse, reducing the number of potentially dangerous connections.
uBlock Origin is installed from your browser's extension store and, by default, already includes highly efficient blocklists with low resource consumptionAdditionally, you can add custom lists or adjust its behavior according to your preferences if you want to fine-tune it.
However, keep in mind that uBlock Origin only protects what happens through the browser. To cover all system applications, you need to combine it with DNS filtering, a solution like NextDNS, or a network-level blocker like Pi-hole.
For home networks, setting up a Pi-hole or configuring NextDNS on the router allows you to all connected devices (mobile phones, televisions, consoles, smart speakers…) They benefit from the lock without you having to touch anything on each device. It's especially useful for gadgets where you can't install extensions or locking apps.
In a context where every click leaves a trace and companies compete to learn more about you, combining these layers—private DNS, email client blocking, aliases, extensions, and local network filtering—gives you much greater control over what information is shared and with whomwithout giving up the convenience of using your mobile phone as usual.
These measures together make your device a much less "transparent" environment for advertisers and trackers: from DNS settings that filter tracking domains, to email that blocks invisible pixels, to aliases that prevent your real address from being exposed. Ultimately, the key is to combine several of these strategies in a simple way to Drastically reduce silent surveillance while still using your mobile phone normally..
