- Where email comes from and why we use the @
- How an email address is put together
- How many emails are sent every day
- How much email is spam and how much is phishing
- How much does an email weigh
- Work email and personal email: two different jobs
- How to use email better
- Frequently asked questions
- The bottom line
Around 376 billion emails moved across the world on an average day in 2025, according to Statista, and the forecast for 2026 is close to 424 billion. That is the kind of number you nod at and then forget, so put it in terms you can feel: roughly 4.3 million messages every second, almost half of them junk.
Email is not dying. Every app that was supposed to bury it ran into the same wall, because the address you already own works everywhere, on every device, without anyone’s permission. The format behind it has barely moved since 2008, the year RFC 5322 pinned it down, and the address still uses the @ that Ray Tomlinson picked in 1971.
Here is what the numbers say about email: where it came from, how much of it moves, how much is spam or phishing, how much one message really weighs, and how to stop your inbox from eating your day.
Where email comes from and why we use the @
Ray Tomlinson was an engineer at Bolt Beranek and Newman (BBN) in 1971. Two programs already sat on his desk. SNDMSG left a message for someone on the same machine. CPYNET moved files between machines. Tomlinson wired the two together and sent a message from one ARPANET computer to another. That is where networked email starts, and the Internet Hall of Fame credits him with “inventing networked email”.
He needed a way to tell the user apart from the machine. Keyboards in 1971 carried a symbol almost nobody used: the @. In English it reads “at”, so the address reads as “user at machine”. Half a century later you are still typing it: user@domain.
One thing is worth saying out loud, because it gets repeated wrong all the time. There was no grand project behind email and no million-dollar commission. Tomlinson found the idea interesting and tried it on his own. The rest of that story, ARPANET and the first messages between universities, is told in the history of computing.
The first email and the message nobody remembers
Ask what the first email said and you hit a wall. Nobody knows. Tomlinson has said his test messages were dull and he did not save them, so the exact words are gone. What survived is the part that mattered: a message left one machine and landed on another, inside a system that until then had only carried files. The habit of owning an electronic mailbox and checking it grew out of that experiment, and it is the part you would still recognise today.
A format that has barely changed: RFC 5322
The standard that defines how a message is written is the RFC 5322, “Internet Message Format”, published in October 2008 and built on older documents. It describes the address as local-part@domain, caps every line at 998 characters, recommends staying under 78, and makes only the date and sender fields mandatory. Delivery still rides on protocols such as SMTP, and the layers that carry it are explained in what is TCP/IP.
How an email address is put together
Every address is two halves split by the @. On the left sits the local part, the name of the mailbox inside a domain, chosen by you or by your provider, which may hold letters, digits and a few symbols. On the right sits the domain, the server that handles the mail. You can put a display name in front, such as “Jane Doe”, but that label decides nothing. The pair local-part@domain is what routes the message, and it is the only part that matters technically.
The domain, in turn, is resolved through DNS, the system that turns names you can read into the addresses machines understand. That is why your address keeps working when the company behind it changes servers, and why the same format survived every migration of the networks underneath it.
How many emails are sent every day
The reference figure comes from Statista, built from tracking by industry firms: around 376 billion emails a day in 2025, with a projection of 424 billion for 2026, according to Statista. In orders of magnitude, that works out to roughly 4.3 million messages every second.
| Year | Emails sent and received per day |
|---|---|
| 2024 | 361.6 billion |
| 2025 | 376 billion |
| 2026 (projection) | 424 billion |
The 2024 figure comes from the Email Statistics Report, 2024-2028, which The Radicati Group announced in December 2024: the firm calculates that email users will grow from more than 4.4 billion in 2024 to more than 4.9 billion in 2028.
People have predicted the death of email for twenty years, and it took the punch from instant messaging without folding. It is the one service that asks nothing of the person on the other end. How the two coexisted for years is told in what happened to MSN Messenger.
How much email is spam and how much is phishing
Almost half of the world’s email traffic is junk. According to telemetry from Kaspersky, 44.99% of all emails sent in 2025 were spam, which is about one in two. The word comes from a Monty Python sketch from 1970, where a choir chants “spam” until you want to scream. Computer people borrowed it for repetitive, annoying mail.
The dangerous slice inside that flood is phishing, which poses as a company or a person you trust in order to steal credentials or data. The Data Breach Investigations Report (DBIR) for 2025 puts the share of investigated breaches with a human factor at 60% and estimates that phishing was the initial access vector in around 15% of cases. Kaspersky adds a workplace number: one in ten corporate breaches starts with a phishing email.
Spam and phishing are not the same
Spam is unsolicited mail, almost always advertising sent in bulk. Phishing is a scam dressed up as a legitimate message. It may arrive inside the spam or on its own, and it usually leans on a link or a malicious attachment. The role of email as an entry point for malware is detailed in computer viruses. The difference matters because your defence changes: against spam a good filter is enough, while phishing gets past filters, and no filter can supply the human judgement and the two-step verification that stop it.
How a filter tells spam from real mail
Modern filters do more than read the text. They check whether the sender is who it claims to be, and three standards carry most of that work. SPF, defined in RFC 7208, lets a domain publish which servers may send mail for it. DKIM, in RFC 6376, adds a cryptographic signature so a message cannot be altered in transit without the change showing. DMARC, in RFC 7489, tells the receiving server what to do when those checks fail. Together they make it much harder to send mail that pretends to come from a domain you do not control, which is the trick most phishing needs.
How much does an email weigh
A text email weighs almost nothing. According to the analysis by Litmus, the average HTML runs about 45 KB in emails not optimised for mobile and 53 KB in optimised ones. The real weight comes from the images: on average 2.24 MB (2.7 MB on mobile), far above the code wrapped around them.
Your client sets its own ceiling. Gmail clips a message whose HTML passes 102 KB and caps attachments at 25 MB. Past that, it swaps the file for a link to Google Drive, as Google Support explains. The standard itself limits every line of the message to 998 characters, per RFC 5322. Compress the images and stop sending heavy files by email when you have another route.
Work email and personal email: two different jobs
Personal email arrives more than it goes out. Notices, invoices, subscriptions. Work email demands an answer and competes with everything else on your calendar. In its report on the “infinite workday”, Microsoft calculated, using aggregated Microsoft 365 data, that the average worker receives 117 emails a day, most of them skimmed in under a minute, and that interruptions from email, chat or a meeting arrive, on average, every two minutes. Some 40% of people online at 6 a.m. spend that time checking email, and more than 50 messages a day are sent or read outside working hours.
That mix is why you separate the two worlds. One account for work, one for everything else. Notifications silenced, or at least quiet. Stretches of the day with no email at all. Digital disconnection is not a luxury, and life without the internet for a few days shows what it costs when work follows you home.
How to use email better
Most email trouble comes down to habits rather than tools. These are the ones that pay off the most.
- Distrust urgency. CISA flags haste and fear as the most reliable signs of phishing, the message that demands you act now or threatens a serious consequence if you do not reply.
- Check the sender and the real link, not the text they display. A link can show a legitimate domain and land somewhere else entirely.
- Turn on two-step verification and stop reusing passwords. If one credential leaks, the damage stays small.
- Do not open unexpected attachments, especially documents with macros or executables, even from a contact you know: their account may be compromised.
- Report and delete instead of replying or hitting “unsubscribe” on a suspicious message. Doing that only confirms your address is live.
- Process email in blocks, two or three times a day, instead of answering every notification as it arrives.
- Use different addresses for work, shopping and subscriptions, and keep your main one for what matters.
Frequently asked questions
Who invented email and when?
Ray Tomlinson, in 1971, combining the SNDMSG and CPYNET programs to send messages between two ARPANET machines. He chose the @ to separate the user’s name from the host machine’s, according to the Internet Hall of Fame.
How many emails are sent every day worldwide?
Around 376 billion in 2025, according to Statista, with a forecast of 424 billion for 2026. Email users will grow from more than 4.4 billion in 2024 to more than 4.9 billion in 2028, according to The Radicati Group.
What percentage of email is spam?
Almost half: 44.99% of all emails sent in 2025 were spam, according to Kaspersky telemetry. Phishing is only a part of that traffic, the part that seeks to steal data by impersonating someone.
What is the maximum email attachment size?
In Gmail, 25 MB. If the file is larger, the service replaces it with a link to Google Drive. As for the message itself, Gmail clips HTML over 102 KB and the RFC 5322 standard limits each line to 998 characters.
Is spam the same as phishing?
No. Spam is unsolicited mail, almost always advertising sent in bulk. Phishing is a scam that poses as a trusted entity to steal credentials or data. The first is a nuisance. The second is a security threat.
The bottom line
Email is past fifty and in better shape than most of the apps that were meant to replace it. The numbers are huge, half the traffic is spam, and the format has barely moved since Tomlinson picked the at sign in 1971. None of that changes what you do. Verify the sender before you click, compress the image before you attach it, and give the inbox two or three slots a day instead of your full attention. Email is still the most universal tool on the internet. Treat it like a critical piece of your digital life, because that is what it is.