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Everybody uses it in their lives, but have you ever wondered how email actually works?
As everyday users of email technology, we know that there are 3 main steps to sending an email:
- Person A, the sender, sends the email
- The email goes through the internet
- Person B, the recipient, receives the email
Although it really is that simple, the process of sending and receiving an email is a little more complex, and it’s handled by servers.
Like printers, online games, and websites, emails rely on servers; servers are computer programs that provide a service to other devices, known as clients.
Email servers in particular manage the sending and receiving of messages between different IP addresses by using email protocols.
Email Protocols
Whenever an email is sent, it goes through two email servers: the sender’s and the recipient’s.
The sender’s email server uses a protocol to handle how the email sent and who it’s sent to, whereas the recipient’s email protocol defines how the email is received.
Servers (and all networking applications, for that matter) rely on the use of ports, which are virtual access points for networking. Ports are managed by a computer’s operating software, and each port is associated with a specific process.
Sending an Email
When you hit “send” for an email it goes through an SMTP server — short for simple mail transfer protocol.
In the past, SMTP used port 25 for outbound emails, but now it uses port 587 for encrypted email transmissions, offering more security.
Email service providers also support the use of port 2525 as an alternative to port 587, if it’s ever blocked.
Receiving an Email
After sending an email, the recipient’s server is responsible for downloading the email to their inbox.
There are two protocols that can be used to manage the receipt of an email, post office protocol (POP) and internet message access protocol (IMAP).
About POP
The current version of POP in use today is POP3, which uses port 110 by default to receive non-encrypted messages, and 995 for secure messages.
POP is simple in that when an email reaches the inbound server, it downloads the email to your device, deletes it from the server, and then disconnects from the internet.
Because the email is downloaded to your device, you’ll be able to view the email even if you’re not connected to the internet.
This has a few advantages:
- low reliance on an internet connection
- quick access to emails and attachments
- doesn’t require much server storage
However, because emails are downloaded to your device, so are its attachments.
This creates a security risk for malicious emails with virus attachments.
Additionally, since the emails are downloaded to your device then deleted from the server, you won’t be able to access the same email from another device.
For this reason, POP is better suited for small operations or a one-person businesses.
About IMAP
IMAP4 is the latest version of IMAP in use, and like POP3 it uses two ports: port 143 by default without encryption and port 993 for secure messaging.
Unlike POP however, received emails are typically kept on the server and can therefore be accessed from any device, which is what most people need for everyday use.
Under IMAP, emails are only downloaded when they’re opened from your inbox.
Although this means accessing emails can be slower (especially for larger emails or slower internet speeds), you’ll also be more protected against malicious emails.
In Summary
So how do emails work?
- emails are sent using an SMTP server
- emails traverse the internet before reaching the recipient
- emails are then received using either a POP3 or IMAP4 server
POP servers have low reliance on an internet connection because received emails are downloaded from the server to your device. They are more appropriate for one-person teams or small-businesses due to limited accessibility and low security.
IMAP servers can sync your emails across all devices but rely on a constant internet connection. This is a more suitable protocol for large companies or any operation that relies on constant email communication.
Generally, email platforms and tools set this is up for us so that we don’t have to worry about it, but it’s important information for email marketers to understand.
That’s why marketing agencies rely on our white label email marketing services, so that they can deliver value to their clients while we handle all the technical stuff.