how email works

How Does Email Work?

Micaela Wright-Hansen

Reading time: about 4 min


  • IT and Engineering

It’s Monday morning. You sit down at your computer to tackle the mountain of emails that poured in over the weekend. After replying to your colleagues with a few perfectly placed cat GIFs, you’re on your way to tackle whichever project is next.


But have you ever thought about what actually happens when you hit “send”? Maybe you haven’t — and maybe you don’t care — but I can guarantee you there are people at your company who do — and they also care about what you do with your personal email (stay tuned for another article on what your email marketer wishes you knew).

Sending an email often happens at close to the speed of light, but there are a lot of steps in between you hitting send and the recipient seeing that adorable cat GIF.

The process

Check out the Lucidchart diagram below for a summary of this process.

The first thing you need is an email client — think Gmail, Yahoo, etc. This is where you type up an email and hit send.

From the client, the email is delivered to a simple mail transfer protocol (SMTP) server where it is queued to be processed. Once the email is processed, the server needs to look up where the receiving domain is located. This is done with a domain name system (DNS), which returns the IP address of where the email is going back to the SMTP server.

Now, the SMTP server knows where to send your email. The next step is for your SMTP server to connect with the recipient's SMTP server.

The IP address is delivered to your router and finds the fastest path to your recipient’s inbox. The email is then passed through a firewall into the internet — where it hops from router to router until it reaches your recipient’s firewall.

The firewall passes your email to the recipient’s router, which directs it to the recipient’s SMTP server. The SMTP server checks with a DNS server, which validates the sender is who they say they are; if they are valid, the SMTP says it’s ok to send the email.

Important note: All of this happens before the email is actually sent. It happens just to establish a connection. Basically the SMTP servers are just saying a pleasant hello to each other.

Once the receiving DNS says it’s ok to send an email, the sending SMTP pushes the email to the router for delivery.

The router breaks the email into individual packets, making it easier to deliver the email.

The packets are then sent one at a time through the process already described above. Once it reaches the recipient’s router, the packets are put back together and transferred to the recipient’s SMTP server.

The recipient’s SMTP server checks the domain against an internal spam list and/or an external spam database. If it passes this initial spam test, it is queued to go to a POP3 Mail Server (post office protocol 3), which is used to receive emails to a local email client. This server allows you to download the email message to your local computer. It is checked by a few more spam filters before being viewed in the recipient’s email client — and they can finally see that adorable cat GIF.

Again, keep in mind — this process happens insanely fast. Think about this the next time you draft up an email. What a time to be alive. This Lucidchart diagram summarizes the process we just discussed.

how email works diagram

So what?

Now — why should you care about any of this? What you send, especially through your corporate domain, affects the deliverability of your marketing emails, which at most companies are an important part of the lead acquisition and nurturing process. If you send a bunch of crappy emails to fake email addresses or email addresses that don’t want to hear from you, not only are you breaking CAN-SPAM regulation, but you’re also hurting your business. Spam complaints and hard bounces mean your future emails won’t get delivered. I can promise your sales and marketing teams will not be pleased about that. This is one of the few times you should NOT follow Nike’s advice.


About the author

Micaela Wright-Hansen is a Sr. Digital Marketing Specialist at Lucid Software, makers of top-ranked productivity apps like Lucidchart. At Lucid, Micaela is responsible for all marketing automation for Lucidchart, from product selling and education to outbound lead gen for the growing sales team. Prior to working at Lucid, Micaela attended the University of Texas at Austin (Hook ‘Em) where she completed the Texas Media program. Outside of work, Micaela is a rabid tennis and football fan and enjoys reading and cooking.

About Lucidchart

Lucidchart, a cloud-based intelligent diagramming application, is a core component of Lucid Software's Visual Collaboration Suite. This intuitive, cloud-based solution empowers teams to collaborate in real-time to build flowcharts, mockups, UML diagrams, customer journey maps, and more. Lucidchart propels teams forward to build the future faster. Lucid is proud to serve top businesses around the world, including customers such as Google, GE, and NBC Universal, and 99% of the Fortune 500. Lucid partners with industry leaders, including Google, Atlassian, and Microsoft. Since its founding, Lucid has received numerous awards for its products, business, and workplace culture. For more information, visit

Related articles

  • How to Increase Sales With Real-Time Email Validation

    Many web apps annoy you by making you re-enter your email and password when signing up. Some also make you stop what you are doing to click a link in a test email to verify the address works. How often have you given up at that point, or gotten distracted before getting around to finishing the sign-up flow and never ended up using a product?

  • Email for Startups: Email Automation Without Customer Detonation

    Startups often have a very limited marketing budget (if it exists at all) but still need to have killer marketing. Inbound marketing is a fantastic way to generate new business without breaking the bank. Done right, inbound marketing can be very good for your startup’s bottom line and your brand.

Bring your bright ideas to life.

Sign up free

or continue with

Sign in with GoogleSign inSign in with MicrosoftSign inSign in with SlackSign in

By registering, you agree to our Terms of Service and you acknowledge that you have read and understand our Privacy Policy.

Get started

  • Pricing
  • Individual
  • Team
  • Enterprise
  • Contact sales
  • linkedin
  • twitter
  • instagram
  • facebook
  • youtube
  • glassdoor
  • tiktok

© 2024 Lucid Software Inc.