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Why Choose Zextras Carbonio CE over Cloud Email Services, Other OSEs, or Zimbra | Carbonio CE

It was between 1832 to 1965 that email transformed from Interoffice to Internet. As time passed, the hardware became smaller and sometimes even invisible (cloud). But the primary purpose remains the same as the email communication with some additional add-ons like, chat, file sharing, group collaboration, video meetings, etc.

In an earlier age, when the cloud was still in its experimental phase or If we say not a comfortable platform, system admins used to manage their own systems on their own premises.

Carbonio CE is the best open source email platform that provides digital sovereignty.

If we do not go into the technicality, email is just the compilation of services & protocols. Whether it is postfix/sendmail, SMTP, POP/IMAP, or anything else. So in the earlier days of system admin, they had to install and configure all the backend mechanisms by themselves using CLI (Command line Interface). But there was still something missing!

The interface

Carbonio CE has feature rich and user friendly interface and experience.

So, the system admins had to use SquirrelMail, Horde, Roundcube, and some other less familiar mechanisms.  

But overall compiling and combining all of these are not only complex but also inconvenient.

Then comes Zimbra with a convenient way to put everything together on the go. But as you have heard by now, Zimbra Open-Source Edition is going to be EOL on 31 Dec 2023.

Carbonio CE is the best alternative after (Zimbra EOL on December 31 2023)

So, what are the best options now?

Let’s bring this discussion forward case by case:

From a Technical Point of View

If you are still thinking of sticking to Zimbra OSE

EOL on 31 December 2023 means no security patch, no update, no upgrade, and most of all no official support from Zimbra.

Just to give you a rough idea, let us present some CVE (Common Vulnerabilities and Exposures) related data of Zimbra for recent two years:

Important Note:
Max Base Score: A higher value means other vulnerability metrics are going to be worse.
EPSS: The higher the value is, the greater the probability that the vulnerability will be exploited.

Reported CVEs In the year 2023: 11
Reported CVEs In the year 2022: 17

And even some of them have higher Max Base Score as well as EPSS values. like:

CVE NameDescriptionMax Base
CVE-2022-41352An attacker can upload arbitrary files through amavisd via a cpio loophole that can lead to incorrect access to any other user accounts.9.896.61%
CVE-2022-37042An attacker can upload arbitrary files to the system, leading to directory traversal and remote code execution.9.897.49%
CVE-2022-27925An authenticated user with administrator rights has the ability to upload arbitrary files to the system, leading to directory traversal.7.296.84%
CVE-2023-29381Allows a remote attacker to escalate privileges and obtain sensitive information via the password and 2FA parameters9.80.12%
***Source: https://www.cvedetails.com

So, we leave this decision to you. Would you be comfortable knowing your server might be exposed to exploiters and may have vulnerabilities that cannot be patched?

Exploring open-source solutions

Currently, we have a few open-source alternatives of Zimbra available in the public domain if we name a few of them i.e. Carbonio CE, IceWrap Mail, Mailcow, Openwave, etc.

Why not take the opportunity to explore them?

All of them have their own pros and cons but if we summarize them in layman’s terms the scenario will look something like this:

  • Most of them are platform agnostic hence you can deploy them on both on-premises and private/public cloud. However, not all of them are fully compatible with GDPR compliance and some offer conditional compliance. So, in the current Geo-political unrest, wouldn’t it be better to have a fully GDPR-compliant solution to protect your data and digital sovereignty? And who’s better than Carbonio CE to ensure full proof of GDPR compliance for your system?
  • Some of these solutions do not support all types of virtualization (i.e. VMWare, XenServer, KVM, Microsoft Hyper-V). Though some support containerization you consider current data-center use cases you will find Carbonio CE is compatible with all of this virtualization.
  • One of the critical differences between Carbonio CE with other open-source solutions is that Carbonio CE has its own dedicated IOS/Android mobile app.
  • The main difference between Carbonio CE and other open-source solutions is the web interface. Carbonio CE has a very feature-rich webmail interface for users and the most customizable Admin UI interface for admins.
  • Most of the other solutions focus on basic email, contacts & calendar-related functions. But Carbonio CE made these basic features more useful by enhancing their functionality like:
    • Multiple/Shared address books
    • Multiple/Sharable calendars
    • Shared accounts/folders
  • While focusing on basic features like mail, contacts, and calendars other solutions miss an important feature which is Files. Carbonio CE Files is not only a generic file feature but is more like a full-fledged enterprise-grade file server enriched with file versioning, sharing internally/externally, and Expiry data on the shared items. Due to the integration of Libre Office (As Docs Server), Carbonio CE Files allows multiple users to collaborate in real-time even on a single file.
  • When we are talking about collaboration, we can not exclude the importance and usefulness of Chat. As we mentioned earlier, other open-source solutions are more focused on basic functionalities hence, most of them lack chat. However, this is not the case with Carbonio CE. Carbonio CE chat allows users to send text messages in 1:1 or group format.
  • Unlike other solutions, Carbonio CE provides advanced storage management with many exclusive features. Like:
    • Support from AWS S3 / Overall S3 / Scality / 3rd party cloud storage
    • HSM/Deduplication/Indexing
  • Multi-tenancy, Granular Administration rights, and User management through COS is never more convenient for anyone else than Carbonio CE

What about cloud solutions?

We need to be a little pragmatic now. Cloud solutions like Google Workspace, and Microsoft 365 are top-tier digital collaboration platforms. They offer all the features that most open-source solutions offer.

But there is a catch.

  • We can not deploy them in any on-premises data centers. Especially, in cases organizations like central banks, govt. agencies etc. are regulated by law to have their email server at their own data center or within the country’s govt. approved data-center.
  • While Geo-political alignment shifts more frequently, all countries are concerned about their citizen’s data. As a result, we can see many countries in Europe (i.e. Denmark, Germany, Netherlands, etc.) are refraining their public and private organizations from using cloud-based email services in order to protect their digital sovereignty.

Note: Europe steps up fight for digital sovereignty, bans 365 and Workspace in more places.

List of EU countries fighting for data privacy:

  • France
  • Denmark
  • Germany
  • The Netherland

***Source: https://nextcloud.com/blog/europe-steps-up-fight-for-digital-sovereignty-bans-365-and-workspace-in-more-places

  • Another important limitation of these cloud solutions is limited control over the customization of the solution. Though these platforms provide you with an admin panel even with the highest admin privilege you can not modify some of its core parameters. In simple words, Open source offers you more power, control, and ability to customize your system than these cloud solutions.

So, these are the technical aspects that make Carbonio CE more preferred solution over other open source or even in some cases cloud platforms.

From a Financial Point of View

Technical pros and cons are important but most of the time the decision of choosing any solution is highly dependent on the financial point of view.

This is where comes the debate/comparison of OPEX & CAPEX:

Carbonio CE provides you the advantage with the capex and the best ROI.

OPEX vs. CAPEX is more relevant when you compare cloud platforms and open-source on-premises solutions. Let’s give you some real-life scenarios so that we can understand how deciding capex and opex can be a decisive factor for solution selection.

The company chooses the Opex route by choosing a cloud provider as their email solution and leases the equipment on the cloud. While the initial cost is low it has some drawbacks:

  • The OPEX cost will add up over time as the organization grows. For each new employee, the resources needed to support him with IT tools (email, storage, etc.) will add costs to the organization’s overall budget.
  • Also, the fluctuation of global resources and currency inflation will contribute to this situation and increase the operational cost of each account.
  • And most importantly, Opex works in a perpetual and recurring manner. So, it does not matter whether your business is booming or going through a rough stage you have to meet and fulfill your operational expenditure.

So, though Opex can be visibly small initially its perpetual, recurring, per mailbox/employee model can make it a tough business decision over time.

Now if the company decides to invest in the data center equipment using Capex. They purchase the servers, networking gear, and storage devices. This makes the initial upfront cost higher but helps you in the future by:

  • Getting you full ownership of your equipment
  • No additional cost for a new user account/storage
  • No annoying recurring or perpetual costs so it can give you some relief if you are going through a difficult phase with your business.
  • Host as many domains/compatible services in your infrastructure without any additional pay.

Even an on-premises server can help service providers create a multi-tenant environment for very small businesses when they only have domains can’t need a dedicated enterprise solution and can’t afford the enterprise-level costing.

In short, a service provider can host hundreds of small businesses on an on-premises server with a cost that can beat the cloud cost quite easily.

We do not agree with it entirely as this concept may have been more relevant a decade ago but now investing in IT management and maintenance is inevitable regardless of your cloud or on-premises service.

So, we hope you got the idea of why on-premises solutions, and especially Carbonio CE can help small and even medium businesses to thrive during their tough days.

Let’s quickly review the standout features of Carbonio CE compared to others:

  • Platform agnostic but still fully compliant with GDPR
  • Supports all types of virtualization
  • State-of-the-art architecture with service mesh technology
  • Dedicated IOS/Android App
  • Modern, user-friendly UI for users
  • Most customizable system with both CLI and feature-rich Admin UI
  • Integrated/Built-in open-source monitoring tool (Prometheus)
  • A built-in full-fledged file server with exclusive features i.e. versioning and sharing.
  • A built-in doc server for real-time, multi-user collaboration.
  • Supports the most widely used external storage. i.e Amazon S3
  • All basic features like email, contacts, calendar, chat, and files but with additional functionality/customization.
  • Multi-server and multi-tenancy provide additional scalability.
  • Multiple verified migration tools are available in the public domain to assist system admins in migrating to Carbonio CE from any other platform.

and many more ….

Can you imagine any other platform with all these perks with exclusive experience and ROI that too in the community edition?

Give your organization the digital workplace it deserves, with all the features you need for a seamless experience.



I liked Carbonio, but 2 things is stoping Me to adopt it: * "Though some support containerization you consider current data-center use cases you will find Carbonio CE is compatible with all of this virtualization." Carbonio does not support LXD/LXC, i.e., forcing to use a VM exclusivelly to it and loosing tools like snapshots in LXC with ZFS/BTRFS/CEPH. Cloud competitors like DigitalOcean, Hetzner, Contabo, etc does not offers nested virtualization and LXD/LXC or Docker is the only way to run multiple services. * "The main difference between Carbonio CE and other open-source solutions is the web interface. Carbonio CE has a very feature-rich webmail interface for users and the most customizable Admin UI interface for admins." Carbonio does not have a horizontal view panels. Only side by side panels.

Md. Shariful Islam

@alepaes Hi, Thank you for your detailed feedback. We understand the importance of making it compatible with other forms of virtualization environments (i.e. LXC/LDC/Docker/Container). Therefore it's in our product roadmap and we will update you when we implement it via our forum, blog, & email. About the webmail panel position, we are still getting feedback from our users. So we are really glad that you let us know yours. This particular feature has already received several requests and we have it already in our backlog. For now, we are focused on improving the stability of our webUI, I’m sure that you will notice several improvements in the 23.9.0 release. However, we want to assure you that we value our users' feedback. So Thank you for being with us. Do not hesitate to let us now your opinion and feedback on any of our platforms. Thanks again.


> Unlike other solutions, Carbonio CE provides advanced storage management with many exclusive > features. Like: > > Support from AWS S3 / Overall S3 / Scality / 3rd party cloud storage > HSM/Deduplication/Indexing A) HSM is actually included in Carbonio CE? Things I have been thinking as an answer: 1) This is an errata of someone who copied some text from Carbonio. 2) HSM is included in Carbonio CE but this specific part is not open source. So it's free as in free beer but not free as in freedom. B) If the HSM included in Carbonio CE is actually open source can you point us to the associated source code? Thank you very much!


Carbonio CE supports AWS S3 as storage? how to setup that?

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