Pop3, IMAP and Important Email Protocols Explained


When it comes to running your business online you want to have all the tools at your disposal. Email is one of those tools. It can be used as a powerful marketing tool and an open communication channel between you and your customers. But like with all things online you want an email server that is secured and ensures that your privacy. In this quickfire tutorial, we’re going to cover the Email protocols most commonly used on the internet—POP3, IMAP, SMTP and HTTP—each protocol differs in the way that they function.

This tutorial will help you decide which email protocol configuration is best for your email needs.

POP3 and the default POP3 ports

POP3 stands for post office protocol version 3. It is the standard email protocol used to obtain emails from a remote server to a local email client.

woman checking on cellphone
Source: elements.envato

POP3 permits you to download email messages onto your local computer hard drive and read them while offline. A word of note on using POP3 as your email protocol. This means your emails are not only downloaded and stored locally on your hard drive, but also completely removed from the server.

So, if you tend to access your emails from various locations and computers, POP3 is probably not the best email protocol option. Alternatively, POP3 helps to keep your email account space free on your web server.

Automatically POP3 comes with certain ports, the POP3 protocol works on two ports:

  • Port 110 – this is the usual POP3 non-encrypted port;
  • Port 995 –  Connect through this port to use POP3 securely.

IMAP and the default IMAP ports

IMAP stands for the internet message access protocol and is an email protocol commonly used to access emails on a remote web server from a local client. IMAP and POP3 are both the most commonly used internet emailing protocols. All modern email clients and web servers support both IMAP and POP3 respectively.

Unlike POP3 protocol, IMAP simultaneously allows access through multiple clients, whereas POP3 protocol is designed for your email to be retrieved from one application. This is why IMAP is the suitable choice for an email protocol if you’re going to access email from various computers and devices and alternatively, IMAP works better when an email is being managed or accessed by multiple users.

Automatically, the IMAP protocol works on two ports:

  • Port 143 – this is the usual IMAP non-encrypted port;
  • Port 993 –  to connect to IMAP securely you want to use this port.

SMTP and the Default SMTP ports

SMTP stands for simple mail transfer protocol and is the standard for sending emails on the internet. SMTP is a protocol used by a Mail Transfer Agent to send and deliver emails to a recipient’s email server. This protocol is defining email sending and cannot be used for mail receiving.

This protocol is generally used for mail transfers between two servers. This transfer requires no authentication to function, dissimilar from POP3 and IMAP. Certain Internet Service Providers tend to block the default port 25 of SMTP. When this happens the email server also provides an alternate secondary port.

Automatically, the SMTP protocol works on three ports:

  • Port 25 – this is the automatic SMTP non-encrypted port;
  • Port 2525 – sometimes this port is opened on all servers in case port 25 is filtered (by your ISP for example) and you want to send non-encrypted emails with SMTP;
  • Port 465 – Use this port to send messages using SMTP securely.

HTTP and the Default Ports

HTTP stands for hypertext transfer protocol and is the more commonly known protocol on the list. This is not an email specific protocol. However, HTTP is also used for email access using web-based emails.

the text inscription http

Web-based emailing clients like Hotmail or Gmail use HTTP as an email protocol. It helps to retrieve and compose emails from a web-based account. HTTPS is also used as a protocol for sending emails more securely through web-based email clients allowing for an end to end encryption.

The automatic ports for HTTP are:

  • Port 80 – This is default non-encrypted port.
  • Port 443 – Use this is an automatic port for secure connections.
  • Learn more about SSL certificates that enable HTTPS here.

Exchange Account (EAS – Exchange ActiveSync)

Exchange is an email protocol used by Exchange Servers like Microsoft Exchange. Exchange has a few cool functions as an email client with special ports. Exchange will not only sync your email but it also will sync your contacts, calendars, notes and everything you have in the Outlook client. The advantage of using Exchange is that users can have synced copies of everything across multiple devices. You can also download your emails so that you can access and view them in offline mode.

There you have it. Now you’re more knowledgeable of email protocols and you didn’t even have to break a sweat. Talk to your hosting provider about more secure ways to send and receive emails.