We are independent & ad-supported. We may earn a commission for purchases made through our links.

Advertiser Disclosure

Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.

How We Make Money

We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently from our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is a Simple Mail Transfer Protocol?

By Michael Linn
Updated May 16, 2024
Our promise to you
EasyTechJunkie is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At EasyTechJunkie, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Simple Mail Transfer Protocol (SMTP) is a set of instructions or procedures in the Transmission Control Protocol/Internet Protocol (TCP/IP) suite used to facilitate network data transfer. SMTP is used along with Post Office Protocol (POP3) or Internet Message Access Protocol (IMAP) to reliably and efficiently send and receive electronic mail (e-mail) transmissions. The Simple Mail Transfer Protocol usually handles outgoing e-mail while the Post Office Protocol handles incoming messages. IMAP is a more advanced version of POP3.

When e-mail is sent, the message goes to the sender’s SMTP mail servers on Port 25. A port is an address for transmitted data. The sender’s SMTP server transmits the e-mail message to the receiver’s SMTP server, which then hands the message off to the receiver’s local POP3 mail server listening on Port 110. This ability to forward e-mail across networks to remote domains is often called SMTP relaying.

People who use web-based e-mail generally do not have to worry about the mechanics of SMTP relaying because the web server handles it. Users who have e-mail programs on their phones or personal computers generally have to configure their devices to send and receive messages. Web-based e-mail users are usually required to login to authenticate themselves before they are allowed to use their provider’s SMTP servers. This is designed to prevent the sending of massive amounts of e-mail messages or spam.

Many times web-based users utilize a browser to connect to their e-mail account. The browser communicates via the Internet using Hypertext Transfer Protocol (HTTP) with the e-mail provider’s web server. The provider’s web server then relays the message to its SMTP server to be sent.

Sometimes e-mail messages fail to reach their intended destination; in this case, the Simple Mail Transfer Protocol provides a mechanism so the sender will receive an automated bounce message that says their message was undeliverable. There are many reasons for a message delivery to fail. Some reasons could be that the message was identified as spam, the address was misspelled, or the sending or receiving servers were busy. Administrators that send messages using mailing lists containing many recipients may receive many bounce messages. A procedure called variable envelope return path (VERP) can be used to remove bad e-mail addresses from the list.

The Simple Mail Transfer Protocol began in 1971 and ran on the U.S. government’s Advanced Research Projects Agency Network (ARPANET), which is an early predecessor of the Internet. Being able to send messages electronically is considered by some to be the first great application on ARPRNET.

EasyTechJunkie is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.

Discussion Comments

EasyTechJunkie, in your inbox

Our latest articles, guides, and more, delivered daily.

EasyTechJunkie, in your inbox

Our latest articles, guides, and more, delivered daily.