POP vs POP3 – What’s the Difference between these Email Protocols?

POP vs POP3 – What’s the Difference between these Email Protocols? In most cases, Internet users with email accounts have used “client” software (such as Outlook) to access and manage their messages at some point. Before downloading messages from the server, these email clients may require the configuration of Post Office Protocol. In this article, readers will learn the comparison of POP and POP3 and their differences.

What is the Post Office Protocol?

POP is a protocol that local email software clients use to retrieve emails from remote mail servers over TCP/IP connections. With the first version created in 1984, the Post Office Protocol (currently at version 3) has become one of the most popular email protocols used by virtually every email client. Simple configuration, operation and maintenance are the reasons for POP server popularity.

POP3 (updated version of POP) is also used by email servers hosted by Internet service providers to receive and hold subscriber emails. Each time they visit the remote server, these subscribers will use their email client software to check their mailbox and download any emails addressed to them.

Most email clients delete emails from the server once they have been downloaded, though some allow users to specify that emails be copied or saved on the server for a certain period.

For POP3 servers, email clients typically connect to them using the well known port 110. Users can choose between using the STLS command after the protocol initiation stage ng POP3S, which can use TLS (Transport Layer Security) or SSL (Secure Sockets Layer) on TCP port 995 the POP3 server supports encrypted communication.

Post Office Protocol Based Applications

Due to its primary method of storing and receiving email, POP3 is compatible with any email program that has been configured to support it. POP3 is natively supported by Outlook Express and other commonly used email clients.

Several applications can back up email messages on the mail server. Backup of emails from any POP3 or IMAP4 mail server is possible with this feature. An email is downloaded and stored in its self contained EML file containing the email’s body and all attached files with this method.

The History of POP Protocol

The Internet Engineering Task Force published the initial version of Post Office Protocol in 1984 as RFC 918 in a Request for Comments. The developers identified the necessity for a simple and effective technique of retrieving emails from a server at the time. They saw the benefit of reading emails offline rather than visiting the mailbox online.

RFC 937 published Post Office Protocol version 2 in 1985, which was superseded by Version 3 in 1988 with RFC 1081. POP3 was changed multiple times over the next ten years before it was being standardized to the current standard, RFC 1939, released in 1996.

What is the Post Office Protocol 3 (POP3)?

Further in our comparison of POP vs POP3 – What’s the Difference is to check out what is POP3. When a user checks for a new email, the client connects to the POP3 server. The email client then provides the server with its username and password for authentication. When the client connects, it issues a sequence of text based requests to obtain all email messages. It then saves the downloaded messages as new emails on the user’s local machine, deletes the server copies and disconnects from the server.

By default, after the server emails are retrieved, they are erased. As a result, the emails are bound to that specific system and accessing the duplicate emails from an email client on another machine would be impossible. The user could avoid this problem by configuring the email client to save a copy of the emails on the server.

POP frees up a server storage for mailboxes by downloading and deleting emails and attachments at the server’s end whenever the email client checks for new messages. Online email messages stored on the user’s computer have no mailbox size limitations, except for the computer’s hard drive capacity.

Advantages of POP3 (Pros)

  • POP3 has the advantage of downloading emails to the user’s PC. Messages can be read even when the user is not connected to the internet.
  • POP3 accounts allow users to have mailboxes on a server with their domain name.
  • Because attachments have already been downloaded, they may be opened quickly and easily.
  • Less server storage space is required because all emails are saved on the local workstation.
  • The size of your hard drive restricts email storage capacity.
  • Very popular, simple to set up and utilize.

Disadvantages of POP3 (Cons)

  • Inability to access emails from other workstations (unless configured to do so).
  • It can be tough to export the local mail folder to another email client or physical workstation.
  • Email folders can become corrupted, even resulting in the loss of the entire mailbox.
  • Email attachments may contain viruses that can harm a user’s computer if opened locally and their virus scanner cannot identify them.

Even though POP3 has been around since the 1980s, it remains one of the most popular and viable email protocols. By storing the mail on the client’s computer, the user can access the messages offline, and there are no size limitations on the server’s storage. However, viruses in attachments should be avoided because they might pose a substantial security risk to the client’s PC.

What is the Post Office Protocol (POP)?

Further in our comparison of POP vs POP3 is to understand what exactly is POP. It is an abbreviation for “Post Office Protocol.” It is pretty simple to email the POP emailer receives an email, and it saves it until you request it. Simply opening your email aware (e.g., Outlook) and pressing the “email” or button requests the email from the server. The mailgram queries the server if there is any mail waiting for it. If there is, it instructs the server to deliver it to you. POP3 downloads and saves all correspondence from the server’s inbox to your computer. Emails are deleted from the server and only saved locally in your client pro emails. When you are not connected to the internet, you can still send and receive emails.

When the POP server gets your mail request, it forwards the email message to your email program. If you receive an email, it is no longer kept on the server unless you specifically instruct it to preserve a copy.

Advantages of POP (Pros)

  • A local copy of your email.
  • Only a tiny amount of space is necessary (if emails are deleted from the server as they are retrieved email).
  • Consolidation of several email accounts and servers into a single mailbox.

Traditional most personal email systems were set up in this manner. For one thing, online storage used to be prohibitively expensive. It made a lot of sense to delete an email from the server once it had been retrieved elsewhere.

Disadvantages of POP (Cons)

  • No remote copy (emails are destroyed from the server as soon as they are retrieved)
  • No remote web access or synchronization between other programmes or devices
  • All mail is kept in a single (and only one) location.
  • Local copies of messages still necessitate disc space for message storage. Messages stored locally are vulnerable to data loss or security risks.
  • If the device where the mails have been downloaded or saved, crashes or gets stolen, the emails are lost.
  • It can consume resources of the system.

Although POP3 has undergone various improvements and adjustments, its designers have kept the essential premise of a simple protocol with a three stage process during mail retrieval between a client and the server. POP3 is one of the most common mail retrieval systems today because of its simplicity.

POP vs POP3 – Differences between these Email Protocols? Conclusion

In this article we have read about POP vs POP3 and we have learned that the main difference between POP3 and POP is that POP3 is the latest used version protocol. POP and POP3 are similar in a way that a local copy of your data is sent to your email and without the device the emails are lost.  With POP3 it allows users to have mailboxes on a server with their domain name. 


Most leading business and enterprise cloud companies use these protocols to provide different email-related products and services.

There are many other protocols used for sending, receiving, and managing email; however, the protocols discussed in this article are by far the most popular and are sufficient to cover most business email use cases.

Avatar for Hitesh Jethva
Hitesh Jethva

I am a fan of open source technology and have more than 10 years of experience working with Linux and Open Source technologies. I am one of the Linux technical writers for Cloud Infrastructure Services.

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