Mozilla Thunderbird was released over 20 years ago, and since then, it has evolved into a full-blown information manager. Yes, it’s not only a simple email client, and that makes it extremely suitable for productivity. Here’s why you can forget about Outlook, Gmail, or even Mailbird, and make Thunderbird your exclusive email client.

5 Unified folders

You can merge all the folders from multiple emails

Tired of switching between accounts? Thunderbird’s Unified inbox feature helps you forget about all this mess. Many other email clients allow you to add multiple accounts, but Thunderbird takes this further.

It consolidates emails from all your accounts, whether they’re Gmail, Yahoo, Outlook, or others, into a single view. This feature helps you streamline your communication and saves you the hassle of navigating multiple interfaces.

You might think that it may be difficult to know which email comes from one account or another, but you have nothing to worry about. The emails are color-coded for each inbox, so you can’t go wrong with this aspect. To merge the folders, click on the three-dot icon from the top left, right next to the New Message button, and select Folder Mods. You can merge all the folders or just the ones you want.

4 Extended customization options

It goes beyond cosmetic changes

With Thunderbird, you can shape your email client to meet your unique needs. First, you can change its themes, fonts, and color code specific categories of emails. Next, you can use tags to categorize emails. There are some built-in templates, but you may also add new ones.

Lastly, Thunderbird supports add-ons and extensions and provides access to an extensive library. You can change the themes or add features like calendar enhancements or even language translators.

You can go as far as integrating tools like QuickFolders or Smart Templates to help you with workflows and increase your productivity. There is even a Send Later add-on that allows you to do just that: schedule your emails to be sent at a later time and date.

3 Advanced security features

Junk filtering works great

Thunderbird comes with pretty solid security features. Apart from the built-in encryption to protect sensitive messages, the email client has a pretty robust junk mail filtering feature. It works very well on spam and boasts phishing protection to block malicious links.

Interestingly enough, Thunderbird doesn’t enable remote content in emails by default. Remote content may include trackers that can provide the sender with certain sensitive information. For instance, they may disclose whether you’ve viewed the message, details about the applications and platforms you’re using, and even your geographical location.

Of course, you can ignore that and enable the feature, or you may add sender exceptions to be on the safe side. Thunderbird also has a scam detection feature and the option to allow your antivirus to block certain incoming emails.

2 Great search and filters to find email and content

You WILL find the needle in the haystack

I’ve already written some good arguments as to why Thunderbird is a superior email client. However, the best is yet to come because the app really excels in its search capabilities. For example, you can search by keywords in the subject line or body, sender or recipient, attachments, dates, or even custom tags.

Apart from that, you can apply filters to automate email organization. For instance, you can flag important messages or seamlessly move certain categories of emails, such as newsletters or promotions, to a designated folder.

For example, searching for XDA offered me an instant list of all the email exchanges with the organization. But that’s not all; it categorizes them in relation to people, by sent and received, from the calendar, or even related to tasks and assignments. Hey, it even has a great search feature inside its Settings menu!

1 Calendar and task management integration

You don’t need another calendar app

Another huge feature of Thunderbird is its calendar, which comes with great management options. When you enable an email account, the app will also ask you if you want to import the calendar if one is attached. After that, Thunderbird simply merges the calendars from multiple emails with all the appointments, tasks, meetings, and other information you have in there.

Then, you can manage and schedule appointments using the built-in calendar, set reminders for tasks and events, and sync your schedules across multiple devices. You can also install a bidirectional add-on to sync the Google calendar, for instance.

But that’s not all. With Thunderbird, you can also search and filter through events from the calendar. Of course, you also have the option to change how you view the calendar and to show the main tasks on the right-side panel of your main email window. I simply can’t figure out what it’s missing from the Thunderbird calendar.

Thunderbird has all you need and more

Thunderbird has many more features that I didn't get to mention. For instance, it's a cross-platform app that works on Windows, macOS, Linux, Android, and iOS. It basically covers all bases and automatically syncs your emails. I also didn't mention that this is a free and open-source email client with a huge worldwide supporter base. You might not need it, but Thunderbird also comes with a secure tabbed browser.

There are many other features I didn't even discover, but the ones I listed above clearly make Thunderbird a solid contender for the title of the best email client out there. Whether you're going to use it depends on your needs and preferences, but you should nevertheless give it a chance.