Rémi Kokabi | Updated October 7, 2026 | 13 min read

What is Emailing – The Comprehensive Guide


Email is the only piece of 1970s technology still running your pipeline. Every meeting you book, every invoice you chase, every password you reset passes through an inbox. And most people who live in that inbox eight hours a day couldn’t tell you what happens in the two seconds between hitting send and the message landing. I couldn’t either, until a campaign of mine started bouncing and I had to learn what an MX record was at 11pm. MailOver’s 2026 statistics report counts 4.7 billion email users worldwide, up from 4 billion in 2020, which is more than half the global population. (50+ Email Statistics Every Professional Should Know in 2026 - MailOver)
In this post, I’ll walk you through what emailing actually is: where it came from, what happens technically when you send a message, how the channel turned into the backbone of outbound sales, and what you need to do to keep your messages landing in inboxes instead of spam folders. I’ll use real benchmark data where it exists, including our own, and I’ll flag the places where the numbers everyone quotes are quietly broken.

What is electronic mail (Email)

Email, or electronic mail, is a method of exchanging messages and files over the internet. The point is to get a message across, kind of like traditional mail, but faster and cheaper.
You send, the recipient receives, and geography stops mattering. All it takes is an internet connection on both ends.

How does email impact communication?

Email changed how we talk to each other at work and at home. Four things explain why it stuck.
  • Speed. Messages are delivered in seconds, not days.
  • Accessibility. You can reach your inbox from anywhere, at any time. Setting up an account takes seconds and the learning curve is close to zero.
  • Searchability. Every conversation you’ve ever had is stored and retrievable. Type a keyword, a sender, a date, and you have it.
  • Cost. Sending to one person costs the same as sending to a thousand, which is exactly why marketing and sales teams moved in.
Slack and Microsoft Teams each hover around 320 million monthly active users, while email commands 4.7 billion, roughly 14 times the scale. (50+ Email Statistics Every Professional Should Know in 2026 - MailOver) Chat tools took over internal conversations. Email kept everything else.

Origin and history of email

The story starts in the 1960s with the early internet and ends with the inbox you’re probably ignoring right now. Here’s the short version.

Early mail transfer systems

Before email, communication meant physical letters and telegrams. The need for something faster produced the first mail transfer systems, which were the precursors to everything we use today.

From mailing to emailing

The internet turned mail into something you could send without paper or postage. That shift produced the first electronic mail system in the early 1970s, and messages became instant.
Traditional mail didn’t disappear from one day to another, but it is becoming more and more redundant since email is a faster and cheaper way to communicate.

Mobile email usage and email clients

Smartphones made email portable, so people started reading messages in queues, taxis and meetings. Email clients (software applications that manage a user’s email) made it manageable, with Outlook and Gmail offering interfaces and features that go well beyond send and receive. Mail transfer protocols standardized the whole process, which is what made email reliable enough to run a business on.

How email history produced the outbound sales stack

Here’s the part most histories skip. The moment email became cheap, instant and searchable, it stopped being a correspondence tool and became a distribution channel. Newsletters came first. Then marketing automation. Then, once anyone could find a prospect’s professional address, outbound sales tooling: sequencers, warm-up tools, verification APIs, deliverability monitors.
Every one of those products exists because of a design decision made in the 1970s, when the protocol was built for a small, trusted network with no spam problem. The gap between that original design and how we use email now is the reason deliverability is a job title today.

From personal messages to marketing

Email now sits in every corner of life. Personally, it’s how you share files and stay in touch. In education, it’s how students and teachers talk outside the classroom.
In business, it’s load-bearing. Internal communication, customer service, recruitment, invoices, newsletters, promotional campaigns and cold emails all run through it. You can reach a large number of people quickly and at a very low cost, and finding a prospect’s address is no longer the hard part. lemlist’s Email Finder and Verifier returns a verified address so your message reaches a real inbox instead of bouncing.

Email marketing

One of the most powerful uses of email in business is email marketing: sending commercial messages to a group of people to promote products, share news, or build relationships.
Doing it well comes down to writing content people want to open, building a clean list, and watching the right numbers.
That last part needs a warning. When we looked at key metrics like open rates, we found the metric has broken down. According to Litmus’ May 2026 email client market share report, based on more than a billion tracked opens, Apple accounts for 64.66% of all tracked email opens, because Apple Mail Privacy Protection pre-fetches tracking pixels at delivery whether or not anyone reads the message. (Apple Mail now fakes 64.66% of your email opens: why cold email open rates lie (and what to track instead)) So the open rate you’re reporting to your boss is part fiction. Track replies instead.
You also have to comply with the law. Get consent, give people an obvious way to opt out, and keep your sending reputation clean enough that your messages actually arrive.
Despite the rise of social media, email marketing remains one of the strongest digital channels. It gives you a direct line to customers and a high return on investment.

Email inside multichannel outbound

Treating email as a standalone channel is how most sequences die. A prospect ignores email one, ignores email two, and you’ve burned the lead.
What works now is coordination. You send the first email, view the prospect’s LinkedIn profile and send a connection request, call once they’ve engaged, follow up on WhatsApp or SMS if the deal is warm enough to justify it. Same message, four touchpoints, each one making the next feel less cold. That’s what multichannel prospecting does: it runs the whole sequence from one place so the channels talk to each other instead of repeating each other.
Email stays the backbone. It just stopped working alone.

Email functionality

To understand how a message travels, start with the email client.
An email client, also known as a mail user agent, is the application you use to send, receive and organize emails. Microsoft Outlook, Apple Mail and Gmail are the familiar ones. The client is your interface. Your emails actually live on a server.

From sender to recipient

When you hit send, your client hands the message to your email server using SMTP (Simple Mail Transfer Protocol).
Your server passes it to the recipient’s server. Their client then pulls it down using POP (Post Office Protocol) or IMAP (Internet Message Access Protocol).
It sounds like a lot of handoffs for something that takes two seconds. It is. And the process is identical whether you’re sending a note to your mother or a proposal to a CFO.

Email protocols: SMTP, DNS, MX, POP, and IMAP

SMTP sends. POP and IMAP receive. But getting to the right server takes a second layer: DNS (Domain Name System) and MX (Mail Exchange) records.
DNS translates domain names into IP addresses. MX records tell the sending server which machine handles mail for that domain. Get them wrong and your message goes nowhere, or worse, lands in spam while your dashboard says “delivered.”
This is where protocol knowledge turns into revenue. Authentication records like SPF, DKIM and DMARC are what mailbox providers check before deciding whether you’re a legitimate sender. If you send at volume, you want those records verified before a campaign goes out, not after. lemlist’s Deliverability Hub checks your setup, warms your domain and flags reputation drops before they cost you a quarter.

How to write and email

Components of an email

An email is more than text. Four layers make it work, and only two of them are visible to you.
  • The SMTP envelope. Invisible to the end user, it carries the sender and recipient information the servers need for routing.
  • The header. What you see at the top: sender, recipient, date and subject line. It also carries technical data like the message ID and the chain of mail servers the email passed through.
  • The body. The actual message content, in plain text, HTML, or both depending on the client settings. Plain text is the simplest form, with no formatting or images.
  • The MIME layer. Multipurpose Internet Mail Extensions is what lets an email carry attachments, images and rich formatting instead of plain ASCII.
In cold outreach, the header does most of the heavy lifting. A prospect sees your name, your subject line and maybe a preview line before deciding. Write the subject line for one specific person, keep the first sentence about them rather than about you, and keep the body short enough to read on a phone.

Attachments and email content

Attachments are files sent along with the message: documents, images, audio, video. Business and marketing emails go further, with images, links and interactive elements like buttons and forms. All of it runs on the MIME standard, which extended the original email format well beyond text.
Typing a message and hitting send triggers a whole chain of technology working behind the scenes to make it happen. Knowing which part of that chain breaks is what separates someone who “sends emails” from someone who gets replies.

Email security

Email carries risk, and the most common form of it is spam.
Spam is unsolicited bulk messaging, usually commercial. Some of it is merely annoying. Some of it carries phishing scams or malware.
Either way it costs you. Spam clogs inboxes, slows down productivity, and exposes people to harmful content. Knowing how to spot it matters, and so does knowing how to avoid sending something that looks like it.

Phishing, Domain Spoofing, Malware, Spam

Phishing emails try to trick people into handing over sensitive information such as passwords or credit card numbers.
Domain spoofing uses a fake sender address that appears legitimate, usually as part of a phishing attack. Malware arrives hidden in attachments or links.
And spam, as covered above, is the unsolicited bulk category that can quietly contain either of the first two. Awareness is the baseline defence. Filters catch the rest.

Email security and management

Email Security Measures for Users

Your email address is a key asset. It’s your main line of communication and the recovery key to most of your online accounts.
So protect it properly. Use strong, unique passwords. Turn on two-factor authentication wherever it’s offered. Review your account’s security settings on a schedule rather than after an incident. And treat every unexpected link or attachment as guilty until proven otherwise.

Encryption methods: TLS, E2EE

Encryption scrambles your message so only the intended recipient can read it. Two methods dominate: Transport Layer Security (TLS) and End-to-End Encryption (E2EE).
TLS encrypts the connection between the client and the server, protecting data while it moves. E2EE encrypts the content at the sender’s end and decrypts it only at the recipient’s end, so an intercepted message stays unreadable.

Overview of 3rd Party Email Security Tools

Built-in protections in clients and servers cover a lot. Third-party tools go further, adding advanced spam filters, phishing protection and stronger encryption options. Some integrate with your existing client. Others run independently.
For senders, the equivalent concern is reputation rather than inbound threats. If your domain starts getting flagged, you want to know the same day, not when pipeline dries up. lemlist’s monitoring and alerts watch your sending health, authentication records and placement, then warn you before a problem compounds.
Whatever you pick, match the tool to what you actually do with email and to what you can afford. Next, I’ll walk through practical tips for optimizing your email usage, from setting up your account to managing your list.

Optimize your email

A clean inbox is a productivity feature, not an aesthetic one.
Delete or archive what you’ll never read again. Categorize the rest into folders or labels. Learn your client’s search operators, because searching well beats filing obsessively. I archive everything older than 30 days and have never once regretted it.
For business accounts, add a few habits on top. Keep a professional tone. Reply within a window you can actually sustain. Don’t send sensitive information over email unless it’s encrypted.
Deliverability deserves its own habits if you send at any volume. Warm new domains before you use them for outreach. Verify addresses before you send so bounces stay low. Cap your daily sending per mailbox instead of blasting from a single address. Write like a human, because spam filters are very good at recognizing a template.

Set up an email client, create organized inboxes and manage your email list

An email client does more than display messages. Outlook, Gmail and Thunderbird let you run multiple accounts, schedule sends, build custom folders and labels, and automate the boring parts.
Once it’s set up, build the structure. Filters that sort incoming mail automatically. Labels or folders by type of message. Stars or flags for anything that needs action today.
List management matters just as much for business accounts. Remove inactive and invalid addresses regularly. Segment by customer type, purchase history, or whatever criteria actually change your message. Then personalize, because a relevant email to 200 people beats a generic one to 2,000.

The future of emails

Automation already handles scheduling, bulk sending and simple replies. AI is now inside the clients themselves, powering smart replies, predictive text and spam detection.
On the sending side, the same shift is happening. With lemlist you can build automatic sequences that react to triggers you set: stop when a prospect replies, send a follow-up after a set number of days, branch depending on behaviour. You can also use AI to write personalized messages at scale, which saves hours and makes the first touch land better.
One caution, since I’ve watched teams learn this the hard way. AI applied to a broken list doesn’t fix it. It just sends the bad message faster.

Final thoughts

Email has turned into a full system for communication, information exchange and revenue. It gives you control over your messages, your relationships and your pipeline, as long as you treat the technical side with the same care as the copy.
Protect the account. Protect the domain. Understand what happens between send and delivery, because that’s where most outbound campaigns quietly fail.
Do that, and emailing stops being a thing you do all day and becomes a channel you can actually predict.
If you’re using email for outbound, Start a 14-day free trial to find verified addresses, check your deliverability setup and run multichannel campaigns from one platform. No credit card required. lemlist is rated 4.6/5 on G2 with more than 2,000 combined reviews across G2, Capterra, and Trustpilot.
Want to go deeper on cold outreach specifically? Join our masterclass and take the concepts here into campaigns that book meetings.
RémiRémi Kokabi
Hi there, I’m Rémi, co-founder of the GTM Club powered by lemlist & Claap. If you believe Go-To-Market is the new moat in this AI-era, you should apply: https://www.thegtmclub.com/
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