What is IMAP and what benefits does the mailbox offer?

Many Internet Service Providers (ISPs), IT professionals, and portals generally recommend opting for the Internet Message Access Protocol (IMAP) over the Post Office Protocol (POP3) when choosing a protocol for managing your email address, citing numerous benefits. These arguments are indeed compelling, as IMAP proves to be very flexible and meets many of the requirements users have for effective inbox management. However, this concept also comes with specific drawbacks that should be considered when deciding between IMAP and POP3, or even other options such as Microsoft Exchange Hosting.

The IMAP protocol integrates a specific file system into the client

IMAP differs from other protocols in more than one aspect. It is not a direct format for transferring information between two endpoints but rather a file system developed specifically for the requirements of email hosting. This means that while emails and their contents can be stored in a database for offline access without network connectivity, this is only used as a secondary option in the absence of synchronisation and primarily serves as a backup. Specifically, IMAP is a special protocol that allows the client to directly integrate the structure on the server. As a result, it supports features commonly found in other file systems, such as:

• Individual distribution of read and write permissions among multiple users
• Hierarchical structuring of folders and subfolders
• Authorisation of users based on different roles
• Real-time permanent storage of information
• Support for specific metadata
• Temporary storage of deleted files in a recycle bin for recovery

Continuous connectivity is necessary with IMAP

Due to its specific functionality, IMAP is a protocol that requires a persistent connection to the mail server to display content or compose new messages. Some clients bypass this issue by creating a local copy and initially editing through it, periodically synchronising with the server or attempting to do so. Once the email address is reachable again, the software syncs the existing data, ensuring both instances match again. However, this approach can lead to problems in certain situations that significantly impact the actual benefits of IMAP. A significant drawback arises in systems with multiple users - where different versions can collide, with changes from one instance inevitably overwriting those of another and thus irreversibly deleting previous versions.

Support for IMAP by Various Clients

Compared to POP3, IMAP is a relatively complex protocol that enables significantly higher functionality, but requires corresponding compatibility between the client and the mail server's properties. The supported functions can vary greatly between servers and various clients. Another issue is that some ISPs deliberately restrict its use to limit the consumption of storage and other resources. While an email address with POP3 is almost always provided for free or at a low cost, some providers charge an additional fee for using IMAP. In this case, they not only incur increased resource costs but also have to store all attachments on their own servers.

Special Advantages of IMAP as a Protocol

Compared to other standards such as POP3, IMAP has numerous advantages. Ultimately, it is a virtual drive that stores all information externally and therefore performs its task perfectly with continuous synchronisation but can cause issues if the connection is interrupted. However, under the given conditions, there are specific advantages such as:

• Simultaneous display on multiple devices
• Availability of a hierarchical folder structure
• Automatic synchronisation when accessed by multiple, different clients
• Setting up multiple users with different rights
• Local storage of messages
• Permanent connection to the server required for every action

In most cases, using the protocol is advisable if offered by a provider for their servers. The advantages over POP3 are numerous, with significant disadvantages primarily for the ISP.

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