How does email delivery work?
The actual journey of an email from the sender to the receiver is not as simple as it looks.
Let’s take an example. You are sending an email to me. In this case, you are the sender, and I am the receiver.
You have typed your message and clicked send. When the email leaves your mailbox (sender’s mailbox), your email gets sent to the outgoing mail server using the SMTP (Simple Mail Transfer Protocol) server. The SMTP is a set of protocol guidelines that your message needs to follow.
For domain verification, the SMTP server contacts the DNS (Domain Name System), which is like a phone book on the internet. It looks through the online directory to identify the sending domain and whether it can be trusted or not. After domain identification, our servers will do an authentication check of records such as SPF, DKIM, and DMARC. Many email service providers offer an in-built authentication system for setting up these records. These records help servers prevent harmful spam, forgery, and phishing.
Based on this exchange of information, my server (receiving server) will decide:
- Whether the message can be delivered (in case of successful identification of the sending domain) or should be rejected (in case of bounce).
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Where should the message go i.e., to the inbox or some other folder?
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When can the message be delivered, i.e., right now or later (in case of deferred messages).