About

This page gives you the foundations of the email system.

At the end, you should be able to understand why when you configure your email client, you need to set up:

• The SMTP configuration
• And the pop or imap configuration

How is an email delivered?

If you want to deliver an email to [email protected], you need to:

• Create the email message
• Lookup the MX records for the domain datacadamia.com to find the final SMTP server known as the Mail Exchange (MX)
• Choose the first server by priority
• Connect to a reception port (say 25) and use the SMTP protocol to transmit the message
• The Mail Exchange (MX) will then deliver the message to the local MDA (Mail Delivery Agent) or LMTP daemon to send them in a mailbox

An mailbox (inbox) may be:

• local linux storage
• an imap server
• a rest api
• or any supported sink

From a processing point of view, filters (such as forward it, reject) can be applied:

• by the SMTP server
• or by the MDA (Mail Delivery Agent)

If you do that from your home, you may encounter the following problems:

• The port 25 is blocked by your Internet Service Provider (ISP)
• Your email will be rejected because you are not authentified meaning that:
  • Your email is not signed with DKIM
  • Or your public IP is not in the SPF record
• Your public IP may have a bad reputation and your email will land into the spam folder

That's why most of the time people send their emails from a fixed SMTP server known as a MTA (Message Transfer Agent)

From your desktop client configuration, Emails are:

• sends to the MTA (Message Transfer Agent) SMTP server
• that sends them to the final destination known as the mail Exchange SMTP server
• that sends them to a MDA
• that sends them to their final destination that stores them in a mailbox.

How do you read your email?

Your emails are read from the inbox via a Pop/Imap server and transmitted to your desktop client.