IMAP and POP3 are protocols used to retrieve email from a remote server to a local email client.
Internet Mail Access Protocol (IMAP) is an email protocol allowing email access from any device. IMAP does not download or store email content onto the device. Instead, users read their messages using the email service. Hpmc Comprar
Source: BevSites Opens a new window
Conversely, Post Office Protocol Version 3 (POP3) is the third version of an email protocol that downloads all new emails onto the endpoint device while erasing them from the email service. Once downloaded, the email can be accessed only from the specific endpoint unless the setting is modified by the server administrator.
Before diving into the leading differences between IMAP and POP3, let’s learn more about them.
IMAP is preferred by users who require access to their email from multiple devices. IMAP does not download or store email on the user’s device. Instead, users read their emails directly from the email service. This allows users to check their email from various devices anywhere worldwide, including smartphones, computers, or even temporary access devices (such as a colleague’s laptop).
In IMAP, the email is generally downloaded only once the user “opens” it. Attachments are not downloaded automatically either, thus preserving internet bandwidth and processing power on the user’s device. This gives users a swift and seamless experience while they check their messages.
See More: What Is Whaling Phishing? Definition, Identification and Prevention
POP3 works by establishing a connection with the email service and downloading all new emails onto the endpoint. Once the download is completed, the emails are typically erased from the service unless the administrator modifies the configuration to prevent this from happening.
Essentially, once downloaded, those specific emails can only be accessed on the same endpoint. Linking to the email service from another endpoint would mean no access to the previously downloaded messages on the new device unless the server is specifically configured to retain a copy of messages.
When a user sends an email over POP3, it is also stored locally on their endpoint, and the email service does not retain a copy (unless specifically configured to do so).
See More: What Is a Content Delivery Network (CDN)? Definition, Architecture and Best Practices
IMAP and POP3 are email protocols used to access and manage emails on remote servers. IMAP enables more advanced email management and synchronization across numerous devices, while POP3 is better suited for configurations where emails need to be accessed only from a single device.
Below are the top comparisons between IMAP and POP3.
The IMAP specification is created in the form of a Request for Comments (RFC), essentially a memorandum explaining the implementation of the protocol adopted as a benchmark by the Internet Engineering Task Force (IETF).
Revisions are typically made to RFCs to ensure clarifications and updates are communicated clearly, and the RFCs most relevant to IMAP are RFC 3501 (2003) and RFC 9051 (2021). That is to say, the protocol popularly used even today by leading email clients to synchronize messages is 20 years old.
IMAP has a clear advantage over POP in terms of synchronization because its original purpose was to serve as a better alternative to POP. Its intended design goal was to allow for the manipulation of remote mailboxes as if they were local.
POP works by downloading email to the local device and erasing it from the server, making it hard to manage email across multiple devices. This was not an issue when computers were more of a collective resource (think time-sharing). However, as personal computers increased in popularity, IMAP became more and more necessary.
No record of the first version of IMAP exists anymore, and the first version to become an accepted computing standard was IMAP2, released in 1988.
This version of IMAP operated “online,” which means it required the email client to be linked to the server while the user viewed or modified their messages. It was impossible to synchronize a copy of the mailbox locally and update it when the local machine reconnected to the server. This was because emails were identified using a “sequence” number, which lacked persistence across client sessions.
As dial-up internet gained popularity, however, users needed a way to check their email without using their telephone lines constantly. This was when support for “offline” IMAP4 operations was introduced in 1994. With this revised protocol came persistent message identifiers known as UIDs.
Since then, the basic IMAP protocol has remained largely unchanged, with new functionality added as optional extensions. Some extensions have become standard, but their adoption varies across email service providers.
The goal of developing POP was to create a simple yet effective email protocol for fetching emails from servers. This functionality was distinct from IMAP’s original “online operation” design, allowing users to access their messages offline, albeit on a single device.
POP2 was introduced before IMAP2 in 1985 through RFC 937. By the time IMAP2 came out in 1988, RFC 1081 was published, detailing POP3.
However, POP3 saw revisions for ten years before the final release, with the refined version published in 1996.
Even though POP3 has seen several enhancements since its publication, it has maintained the basic principle of following a three-stage process while fetching emails. It is this simplicity that makes POP3 popular for certain applications even today.
Synchronization entails “universal status continuity.” Let’s say a user opens an email on any of the devices mentioned above — it will also be marked as “opened” on all the other devices. Same with an email being deleted on one device, being replied to, and so on.
This continuity is not limited to emails but extends to folders such as inbox, sent, and junk. Users can even use IMAP to create their own custom folders — these would be visible on all other devices too.
Another key highlight of IMAP functionality is providing flexibility for users accessing their mailboxes — this protocol can operate online, offline, and even when disconnected! The offline and disconnected operating modes make this protocol especially popular.
IMAP accesses and fetches emails from remote servers. This allows users to access their email while a copy is retained on the server side.
Users can set message flags on IMAP. This allows message status (opened, deleted, etc.) to be tracked across devices.
IMAP is useful for managing multiple mailboxes. Users can transfer messages among mailboxes, as well as organize messages into different categories. This has many use cases; for instance, users working on different projects simultaneously can categorize their emails accordingly.
IMAP offers download flexibility. Depending on the configuration, IMAP can let users decide whether emails must be retrieved before fetching them from the server. Additionally, users can download segments of messages, such as a part of the body, from the mime-multi section. This is useful for certain use cases, such as when the short-text email element contains a large multimedia file.
Unlike POP3, IMAP allows users to organize and manage emails on the server side. This includes creating, erasing, and renaming mailboxes on the server as required. Users can also create hierarchies through folder organization.
Searching within the contents of emails is also a functionality of IMAP. This includes the ability to check headers before downloading an email.
However, just like POP3 and a number of other TCP/IP application protocols, IMAP is a client-server protocol. IMAP4 functions only when the protocol resides on the same server as the user mailboxes. Generally, the mailbox must be accessible to Simple Mail Transfer Protocol (SMTP) for incoming emails and IMAP for retrieval and management.
Finally, IMAP leverages the Transmission Control Protocol (TCP) for communication to facilitate the seamless delivery of data and ensure information is received in the order it was transmitted.
If the username record is fetched successfully, the server sends the client an “OK” message and requests a password. Successful password entry from the client side leads to the connection being established successfully.
Once connected, users can view the emails listed on the POP3 server. This list also displays the number of emails and their sizes. The user can then begin fetching the desired emails.
Once an email is retrieved, it is deleted from the server side. Therefore, the emails are restricted to the specific machine onto which they have been downloaded and would not be accessible on other machines. This is the most important difference between IMAP and POP3.
However, modern-day POP3 clients can be configured to retain a copy of the email on the server side, bringing POP3 and IMAP closer in functionality.
A key advantage of POP3 is that it allows users to read emails offline. An internet connection is only required when emails are being downloaded from the server. Once the download is complete, the emails are stored locally on the endpoint and can be accessed without an internet connection. This also means that already downloaded emails can be viewed easily and quickly.
Additionally, POP3 does not limit the size of the emails being sent or received, although individual configurations can put limits in place as required.
Further, POP3 requires less storage space on the server side as emails are transferred for storage on the client side. However, this can cause storage problems on the client side, as the endpoint storage limits the maximum mailbox size.
Finally, POP3’s simplicity makes it popular for certain use cases. It is easy to configure and straightforward to use.
Like many other standards and protocols for internet applications introduced back when the internet was still mostly used for academics and research, IMAP security relied heavily on the users implementing it. And even when users fully comply with the traditional IMAP security expectations, they remain exposed due to its limitations. For instance, some configurations still allow remote users to authenticate themselves using plaintext usernames and passwords.
Of course, most IMAP security issues have been ironed out in the security-conscious post-pandemic enterprise landscape. However, this protocol continues to feature flawed email security measures in some deployments simply because it is so long-prevailing and popular in various environments.
Besides accepting plaintext login credentials, IMAP is also vulnerable because it lacks support for strong authentication, such as multi-factor authentication (MFA) for third-party email clients logging into cloud-hosted IMAP services. An example of this vulnerability is the “password spraying” attacks targeting Microsoft Office 365 users — while Office 365 supports MFA, it can be bypassed by linking to IMAP services using a third-party email client.
Today, the risks associated with IMAP permitting plaintext credentials are mitigated by switching the default configuration to enable implicit TLS encryption for all email protocols. The IMAP over TLS protocol sets a standard for all legacy email protocols to use TLS for encrypting user mail sessions by default or at least use the STARTTLS protocol to implement opportunistic encryption. This protocol is outlined in RFC 8314 and, apart from IMAP, also includes SMTP and POP.
However, requiring TLS is not sufficient by itself for preventing IMAP password spraying attacks, and support for MFA is still thoroughly lacking.
This security limitation is not the only one that can lead to improper configuration and successful cyber attacks. For instance, third-party IMAP clients are not always compatible with Office 365 sign-on policies that restrict remote users from attempting to sign on too many times. This can allow attackers to experiment with brute-force attacks .
So, how can IMAP security be tightened? As with most cybersecurity challenges, awareness of existing issues is the first step to enhancing IMAP security. Exercises geared towards protecting vulnerable systems can begin by identifying the locations where sensitive protocols are deployed. Next, such exercises can work to ensure that these protocols are correctly configured to facilitate encryption either through IMAP over TLS or STARTTLS.
While the default port for IMAP is port 143 for client requests, port 993 is assigned for IMAP over TLS. Reconfiguring servers and clients to use port 993 can assist in eliminating plaintext connections. Firewalls and other gateway systems can also be set to restrict connections with the unsecured port 143.
Finally, other security measures for IMAP should address how IMAP servers can be accessed. Some tactics include:
A key reason for POP3 being considered vulnerable is the local processing of emails. With POP3, data is not synchronized across devices; rather, information is downloaded onto the currently logged-in device, where everything is processed. This makes a user’s email only as secure as the device — if a malicious actor can access the device, email security goes out the window.
Naturally, this is not the only reason for POP3 being considered insecure. A lot of the security issues in this protocol stem from it being almost two decades old. As POP3 falls out of favor and loses support, it is being replaced with newer protocols compatible with newer email security features.
Of course, this does not mean POP3 is completely insecure. Adding TLS or SSL to a POP3 server encrypts the data shared throughout the server. However, unless support for synchronization is enabled manually, emails cannot be accessed across devices, limiting the usefulness of such an exercise.
Why does IMAP win over POP3 in terms of security? Let’s take a look:
Message storage is limited and relies on the user’s hosting plan and mailbox quota allocation. In cases with heavy email usage, users will likely have to pay more for larger mailbox storage.
Email access is slightly more time-consuming than POP3, as all folders are synchronized whenever a Send/Receive event is triggered.
Resource-intensive messages can lead to the local system slowing down.
Configuring POP3 to deliver email to multiple computers means several devices (as well as the server) now host the same data, resulting in duplication of downloading and deleting emails.
See More: What Is Network Topology? Definition, Types With Diagrams, and Selection Best Practices for 2022
IMAP is best for users who need to access their email from multiple devices and want to keep their messages organized and synced across devices. It allows for more sophisticated management of email messages, such as organizing them into folders on the server and synchronizing them across multiple endpoints. IMAP is ideal for users who frequently check their email from multiple devices, such as desktops and smartphones, and want to have the same email experience on all of them.
POP3 is more suited for users who primarily access their email from a single device and want to download messages for offline access. It is a simpler protocol that does not provide the same level of management or synchronization capabilities as IMAP. When a user retrieves their email using POP3, the messages are typically downloaded to the device and then removed from the server. This makes it ideal for users with limited or unreliable internet access, among other use cases.
Both IMAP and POP3 are considered unsecured in terms of cybersecurity but can be made more secure with extensions like SSL and multi-factor authentication. They also differ in terms of history and functionality.
Rdp Powder Did this article help you gain an in-depth understanding of IMAP vs. POP3? Share your feedback on Facebook Opens a new window , Twitter Opens a new window , or LinkedIn Opens a new window .