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What is email transport and how are emails delivered?
Email transport is a set of services and tools responsible for delivering emails from senders to the recipient's server. The recipient can retrieve or view the email in various ways; this is not email transport, but rather email receipt.
Email transport is especially important for mass mailings , when you need to send tens or even hundreds of thousands of emails.
There are three main approaches to implementing email transport:
Your own SMTP server . Simply put, it's like buying your own truck, hiring a driver, and planning your own route (handling logistics). It's inexpensive at scale, but very complex and expensive when it comes to one-time investments. The payback can take several years.
A ready-made SMTP Relay (based on a mailing service). Continuing the analogy, it's like renting a truck with a trusted driver. Some of the technical details are still your responsibility, but there are no one-time investments. You're renting a ready-made solution.
Email API (also powered by a mailing service). It's like sending parcels through an experienced delivery service with a network of pickup points and full-time couriers. You simply hand over the box, and the service takes care of the rest.
More technical details about email transport
If you're familiar with modern websites, you'll understand that they require a browser to display, that pages are stored on servers, and that when accessing these pages, data with specific markup—HTML code—is transmitted over the network. The protocol responsible for this is HTTP(S).
In the case of emails, the process of exchanging information is roughly the same, but with some clarifications:
Emails may travel through a chain of servers, but ultimately they recent mobile phone number data must end up on a mail server that the recipient can access to read them.
To display the content, you need a mail client (it can be implemented as a separate program or as a web interface that runs in a browser).
Various technologies can be used as data transfer protocols—SMTP, POP, IMAP, HTTP(S). They depend on the purpose of the data transfer and the direction of the flow.
With websites, traffic is routed based on the domain and page ID (address). With email, the user ID (their login/nickname, i.e., the first part of the address before the "@" symbol) and email domain are used to find the recipient's email address.
In both cases, domains are involved, and therefore the entire DNS system.
However, since the servers responsible for website and email processing are usually physically separated, different strings are used within the DNS system to specify the correct server. MX records are responsible for addressing mail servers .
So, to deliver email, you need a whole stack of technologies and the corresponding servers. This combination constitutes the email transport (delivery system) .
Now about technology:
To retrieve a letter (to receive email from the destination mail server), two protocols can be used at once – POP or IMAP .