Dovecot IMAP Server

Our pride and joy, Dovecot is an open source email server with an installed base of over 4 million servers all over the world and a global market share of 72% of all IMAP servers (actual study:, Dovecot is the IMAP server of choice for ISPs, Telcos and Enterprises everywhere in the world.

Dovecot is written with security primarily in mind. Dovecot is an excellent choice for both small and large installations. It is fast, simple to set up, requires no special administration and it uses very little memory.

Some of the most notable features of Dovecot open source version include:

  • Dovecot is among the highest performing IMAP servers while still supporting the standard mbox and Maildir formats. The mailboxes are transparently indexed, which gives Dovecot its good performance while still providing full compatibility with existing mailbox handling tools.
  • Dovecot is standards compliant. Dovecot v1.1 passes all IMAP server standard compliancy tests while most other servers fail many of them. Dovecot’s indexes are self-optimizing. They contain exactly what the user’s client commonly needs, no more and no less.
  • Dovecot is self-healing. It tries to fix most of the problems it notices by itself, such as broken index files. The problems are however logged so the administrator can later try to figure out what caused them.
  • Dovecot tries to be admin-friendly. Common error messages are made as easily understandable as possible. Any crash, no matter how it happened, is considered a bug that will be fixed.
  • Dovecot allows mailboxes and their indexes to be modified by multiple computers at the same time, while still performing well. This means that Dovecot works well with clustered filesystems. NFS has caching problems, but you can work around them with director proxies.
  • Postfix 2.3+ and Exim 4.64+ users can do SMTP authentication directly against
    Dovecot’s authentication backend without having to configure it separately.
  • Dovecot supports workarounds for several bugs in IMAP and POP3 clients. Since the workarounds may cause the protocol exchange to be slightly less optimal, you can enable only the workarounds you need.
  • Dovecot is easily extensible. Plugins can add new commands, modify existing behavior, add their own data into index files or even add support for new mailbox formats. For example quota and ACL support are completely implemented as plugins.


Dovecot Pro is the commercial ISP and Telco product of Dovecot Oy. It provides a reliable and scalable Mail Back End to customer installations which have up to tens of millions of mailboxes and millions of concurrent users.

Dovecot Pro customers can license following Dovecot Products:

  • Object Storage Plugins for Amazon S3, Windows Azure, Ceph and more..
  • Dovecot MaaS (Mail as a Service) Elastic Cloud Capability
  • Ability to use the native Scality Ring CDMI connector to replace NFS in private clouds
  • Dovecot Email Archive to generate additional end User revenue
  • Storage Encryption features
  • Upcoming Dovecot MTA for Email Security
  • Dovecot Professional services and custom development
  • Dovecot Expert Team designing, planning and scaling the systems
  • 24/7 Support services

Licencing of these products is simple, the prices are per Mailbox.
Contact us for more details…

Dovecot Object Storage PlugIn (for Dovecot Pro Users)

– Optimized usage of Dovecot with Cloud technologies, such as Windows Azure, Amazon S3 and Scality.

The Dovecot Object Storage Plugin enables your Dovecot email service to store the email data into a Cloud.

Large email providers are under constant pressure to decrease the costs of the email storage.

Low-cost replicated object storage systems have recently surfaced as an alternative to the commonly used expensive SAN/NAS storages, which are the most commonly used storage methods for email systems until today. These new object storage systems usually have higher data access latency and offer much more restrictive methods of accessing the data.

Storage capacity need grows constantly about 40% per year, and if you provide free email solutions to your customers, the financial formula does not add up.

This is why we developed the Dovecot Object Storage Plugins!

Due this high demand for email storage on different cloud storage solutions, we decided to develop a feature that allows Dovecot email server to be used with high-latency object storage database systems.

In this release, we support Windows Azure, Amazon S3 and Scality systems.

Support of more systems are in development.

With the Dovecot Object Storage Plugin, our licensed customers will be able to design storage architecture to meet their requirements in the new world of Cloud storage.


Dovecot Email Archive (for Dovecot Pro Users)

Dovecot email Archive is highly secure, cost efficient and scalable multi-domain email archive solution for Telcos, ISPs and Enterprises. The email archive has an optimized mailbox format (abox) for archiving, which leads to low setup costs as expensive disk / server setups are not needed. Archive has fast search capabilities in order to retrieve the wanted emails in an efficient way.

Key Features of the Dovecot Email Archive:
• Easy setup with low costs, highly scalable solution
• Archive is integrated with customer’s SMTP server
• Optimized mailbox format for archiving (abox)
• Supports all known IMAP and SMTP mail servers
• MULTI-DOMAIN architecture supported
• Can store and retrieve archived data in multiple datacentres in multiple locations
• SMTP Authentication
• SSL Certificate between servers
• Username / Password authentication
• Paranoid-level checks during mail saving

• Fast full-text search of emails and file attachments
• Search filter with time frame, keywords, recipients, sender, etc.
• Search multiple mailboxes
• Search users folders
• Search multiple folders

Archiving methods:
• Automatic archiving of all incoming and outgoing emails
• Emails are archived 1:1 in a MIME-compatible matter with NO loss of information
• 100% transparent for end user
• No performance loss on the regular email traffic
• Emails are stored to INBOX and Sent folders
• Old emails can be imported to the archive

Access methods:
• Standard email clients, webmail, smartphone, tablets, etc.

• AES256 encryption of email bodies and attachments
• SHA256 checksums for all stored data

User functions:
• Recovery and backup download of emails by the user (Web Interface)
• Reply or forward archived emails by opening them directly in email client
• Access to the archives of other employees (based on assigned privileges)

• Suitable for any volume of data and any number of users
• Lower storage requirements by using single instance archiving (duplicate content is only archived once) and compression of file attachments.
• Supports iSCSI, Fibre Channel, NAS, JBOD, and SAN
• Internal application replication

Dovecot IMAP Smart Proxy

Dovecot can be used as a “smart proxy” in front of another IMAP server. In this configuration Dovecot talks to the IMAP client using a standard compliant and extension rich IMAP protocol, while downloading mails from the “real” backend IMAP server using a more simplified IMAP protocol.

Internally the backend IMAP server is treated as just another mail storage backend (like Maildir). This has many uses, including:

Fixing IMAP servers
Dovecot is fully IMAP protocol standards compliant with support for many IMAP extensions. Some servers have only barely implemented the necessary functionality to support the most widely used IMAP clients. Using less common IMAP clients may work badly or not at all with these servers. Many servers also don’t behave correctly with certain mails or with multiple clients accessing the mailbox, which results in poor user experience. If you are not able migrate your IMAP server to Dovecot, you can still easily solve these problems by adding a Dovecot IMAP Proxy in front of your real IMAP server.

Giving secure access to mails via IMAP
Some companies don’t trust their IMAP server enough to make it open to the entire public Internet. VPNs may be allowed, but they may not be supported by all the mobile phones and other devices that employees wish to use. Dovecot has many security hardening features, which provide users’ mail privacy. Opening a hardened Dovecot IMAP Proxy to public Internet has been more acceptable to our customers.

Improving performance with caching
IMAP Proxy uses regular Dovecot index/cache files. This may improve performance for “online” type IMAP clients, such as webmail’s, if the backend IMAP server is slow or has high latency. Mails can also be indexed and searched locally using a full text search index. In future the entire emails may be precached.

Modifying emails on the fly
IMAP Proxy allows plugins to modify the mails before they are sent to IMAP clients. This may be useful for various purposes, such as automatically decrypting encrypted emails for clients that don’t support them.


Dovecot Enterprise Release

Dovecot Enterprise Release is the latest and most recent stable version of Dovecot for enterprise use, packaged by the Dovecot Team. All new features, updates, upgrades, bug fixes, of the open version of Dovecot are certified against all supported client configurations before release to assure total business continuity.

Enterprise releases are updated frequently

• The frequent releases contain only important bug fixes

Enterprise release will be published after successfully passed test series.

• Functional testing
• Tests against customer configuration
• Code security testing
• Software performance testing

Easy and Safe installation and upgrades

• Upgrade tests against different versions


Dovecot Oy | Lars Sonckin Kaari 10 02600 Espoo, Finland | Tel. +358 44 750 1962