Email protocols: SMTP, IMAP, POP3

Email protocols: SMTP, IMAP, POP3

On a daily basis, more than 300 billion emails are sent throughout the world. They are part of our life for many years, but their functioning is still mysterious for most of us. To see a little more clearly, let’s take a look at the main mail protocols that allow the use of emails.

The email world is driven by three major protocols that you may have heard of, although not necessarily knowing what they mean or what they are used for. Here are the three most well-known and commonly used:

  • SMTP : Simple Mail Transfer Protocol
  • POP : Post Office Protocol
  • IMAP : Internet Message Access Protocol

Don’t fret, we won’t bother you with sordid technical stuff! We will explain the role of each protocol and outline their strengths and weaknesses.

The SMTP protocol

SMTP is a communication protocol used for email. To put it simply, SMTP allows us to send / transfer emails on the networks. The mail will be moved from server to server until it reaches its final destination ( known thanks to its email address). We highly recommend you to read our article dedicated to SMTP protocol which will allow you to understand it in greater detail.

In a nutshell, SMTP plays the role of a letter carrier distributing mail to the right recipient, while the next two protocols will focus on mail retrieval. SMTP is therefore THE indispensable protocol used to send emails all over the world and has been used for many years.

The POP3 protocol

POP3, as you probably guessed, is the third iteration of the POP protocol allowing the retrieval of emails. In practice, this protocol will be used to authenticate itself on the mail server, download the messages from it and store them on the client machine.

The email management is done on your device, locally. This allows emails to be read even without an internet connection once they have been downloaded, which can also serve as a backup. The downloaded mails are automatically removed from the mail server, which prevents a saturated mailbox but also makes it impossible to sync and thus complicates the use on multiple devices.

The IMAP protocol

IMAP fulfills the same task as POP3 : retrieve emails, but unlike POP3, all email handling is done directly on the mail server, the mails remain on the server. This means that an internet access is needed for all the actions you perform and offline use is excluded.

The constant connection to the mail server allows you to sync the state of each of your emails. This way, an email seen on your smartphone will also be marked as such on all your other devices/clients. Nowadays, this protocol is particularly convenient with our multiple online devices: checking your mail is done in a seamless fashion.

A protocol for every use

The choice between IMAP and POP3 is at the sole discretion of each individual :

  • The use of IMAP is to be favored if you use more than one device (smartphone, tablet, smartwatch…) in addition to your computer. In our mobile, multi-device and hyper-connected world, the synchronization enabled by this protocol is highly appreciated by many people.
  • POP3 is to be used only for fairly niche uses, where the consultation of a mailbox on several devices is not required or desired.

In terms of security, both IMAP and POP3 offer secure connections via SSL to prevent a malicious third party from intercepting your credentials or data.

As we have seen, SMTP is not tied to IMAP or POP3 but is indispensable to the operation of emails and has no real alternative. SMTP is used to send emails, POP and IMAP to receive them.

Now that SMTP, POP and IMAP protocols have no more secrets for you, try Pacomail free of charge and without any commitment to go further in the conception and testing of your mails. Don’t take the risk of sending real emails during development, rely on Paco.