Who created SMTP?

SMTP or Simple Mail Transfer Protocol was originally created in 1982 by computer scientist Jonathan Bruce Postel as part of the RFC 821 standard which outlined the protocol for the first time in detail. SMTP provided a standardized way for electronic mail transmission between internet hosts and servers.

Postel made pioneering contributions to early Internet protocols which laid the foundation of networking as we know it. His robust and extensible design for SMTP allowed it to endure over four decades and remain the ubiquitous email transmission standard even today.

Who created SMTP?

History of SMTP Creation

The origins of SMTP date back to early days of ARPANET when email first emerged:

  • During 1970s, various incompatible email systems emerged like FTP-based SENDMSG and Mailbox command.
  • Varying standardization efforts attempted with protocols like Mail Protocol in 1977 and NJE (Network Job Entry) in 1978.
  • But none had the qualities needed for a universal email standard. Interoperability issues hampered communications.
  • RFC 788 in November 1981 outlined a ‘Simple Mail Transfer Protocol’ for the first time by Jonathan Postel.
  • It was formalized into the milestone RFC 821 standard in August 1982 that defined the protocol comprehensively.

So SMTP as we know it today traces its roots directly back to initial specifications penned by Postel aimed at unifying email implementations.

About Jonathan B. Postel – Original Creator of SMTP

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Jonathan Bruce Postel was the pioneering computer scientist who authored the SMTP and other defining standards that created the modern Internet.

  • Born in 1943 in southern California. PhD in computer science from UCLA.
  • Joined the Information Sciences Institute at USC in 1973 as a research engineer.
  • Deeply involved with ARPANET, the precursor to today’s Internet.
  • Edited many of the core RFCs (Request for Comments) that became Internet standards.
  • Authored Telnet, FTP, SMTP, DNS, POP3, BGP and other protocols fundamental to Internetworking.
  • Known as the ‘God of Internet’ due to his visionary RFCs and immense influence over its architecture.
  • Postel Award named after him for lifetime impact on Internet progress.

So Postel defined the core DNA of Internet through the SMTP protocol, DNS, addressing frameworks and more created in the 1970s-80s responsible for its eventual success.

Postel’s Contributions to SMTP

Postel made multiple crucial contributions that shaped SMTP:

  • Wrote the defining RFC 821 document in 1982 providing detailed specification of SMTP.
  • Established straightforward text-based commands like ‘MAIL FROM’, ‘RCTP TO’ which remain unchanged still.
  • Chose resilient and stateless client-server model. Still used in modern TCP/IP client-server paradigms.
  • Implemented feature of relaying between intermediate mail hosts – a key enabler for interconnectivity.
  • Adopted domains concept he helped develop for DNS to standardize email addressing.
  • Laid the framework for critical extensions like SMTP over TLS, SMTP AUTH for security.

So Postel via SMTP gave email the interoperability and scalability needed to become an Internet-wide communications mechanism.

Postel’s Achievements and Recognition

In addition to SMTP, Postel made groundbreaking contributions throughout core areas of Internet technology:

  • Published over 200 RFCs spanning from File Transfer Protocol to Domain Names System design.
  • Known as the ‘Editor of RFCs’, he oversaw documentation of many protocols.
  • His leadership of the Internet Assigned Numbers Authority (IANA) from its inception in 1988 ensured Internet’s continued smooth operation for years.
  • Pioneered the concept of protocol layers through his work on TCP/IP framework.
  • Received numerous awards like IEEE Internet Award, ICANN Privacy Award for his profound impact on shaping the Internet.
  • Widely revered as one of the greatest engineers of the 20th century whose immense vision and principles guided the Internet in its formative stages.

So his foundational work on SMTP, DNS, TCP/IP stack, addressing frameworks proved pivotal for expansion of the nascent Internet into the all-pervasive network we know today.

Key Aspects of Postel’s SMTP Design

There were certain key aspects that made SMTP a universal email standard:

  • Text-based – Use of human-readable text commands made debugging easy. Still used today.
  • Stateless – No permanent session state preserved making the protocol resilient. Messages are independent transactions.
  • Client-server – Asymmetry with dedicated always-on servers and on-demand client connections suited distributed email well.
  • Store and forward – Persistent storage of messages enabled asynchronous relaying between hops.
  • No authentication – Anonymous transactions focused just on transmission. Later extensions enhanced security.

So features like simplicity, flexibility and decentralized architecture allowed SMTP to scale globally on the emerging Internet backbones.

Legacy of Postel’s Contributions to this Day

Postel passed away in 1998 but his legacy and influence is still going strong in today’s Internet infrastructure maintained by standards bodies like IETF:

  • SMTP – Still used for routing trillion+ emails sent daily demonstrating robustness of Postel’s design.
  • DNS – Fundamental Internet directory providing domain name lookups built to last.
  • TCP/IP – Layered architecture sets foundation for entire modern networking stack.
  • IANA – Still stewards IP address allocation and Internet standards issues after IANA transition.
  • So his conceptual frameworks and key standards continue to serve as the scaffolding holding up the global Internet decades later as online communications and commerce continue to thrive.

Key Takeaways

  • SMTP was conceptualized and authored by renowned computer scientist Jonathan Bruce Postel in 1982.
  • He wrote the pioneering RFC 821 comprehensively documenting the protocol.
  • Postel also developed several other foundational Internet standards like DNS, TCP/IP, FTP, Telnet etc.
  • His stateless, text-based and decentralized design enabled SMTP to scale globally for Internet email delivery.
  • Features like relaying, enveloping, domain-based addressing, header layout etc. specified by him are still followed today.


The creation of SMTP standards by computing legend Jonathan Postel provided the first universal mechanism to reliably transport emails over the nascent Internet between disparate systems. By offering a common language for global mail exchange irrespective of internal system details, SMTP fulfilled a profound need in making electronic communication ubiquitous. It embodied Postel’s simple yet resilient approach seen across his transformative RFCs which shaped the evolutionary path of the Internet. With email itself relying absolutely on SMTP till date after four decades to send trillions of messages across the world, Postel’s timeless design choices have definitively stood the test of time.


  1. Who currently maintains the SMTP RFC standards?
    The original SMTP RFCs authored by Jon Postel are now maintained by the IETF within the Internet Standards Process under its Network Working Group focused on email-related specifications.
  2. Have any aspects of original SMTP changed over time?
    The core protocol commands, enveloping approach and message formatting principles formulated by Postel in SMTP remain identical still providing a framework for extensions like ESMTP, SMTPS etc.
  3. What was the first version of SMTP?
    The first outline of SMTP was published by Postel in 1981 as RFC 788. This was expanded as RFC 821 in 1982 which specified version 1 comprehensively and is considered the defining version.
  4. Who controls changes to SMTP standards now?
    The Internet Engineering Task Force (IETF) now controls changes and updates to SMTP through proposals called RFCs and community reviews by networking experts.
  5. What was the impact of SMTP on early Internet?
    SMTP provided the missing standardization that allowed disparate mail systems to interoperate globally, making electronic communications over Internet possible. This drove email adoption.
  6. Are any of Postel’s RFCs still used on Internet?
    Yes, foundational standards like SMTP, DNS, Telnet, FTP etc. authored by Postel as RFCs decades ago still underpin key Internet protocols and systems functioning today.
  7. What was Postel’s contribution to DNS?
    Postel authored the original Domain Name System design in RFCs that created the DNS hierarchy enabling mapping domain names to IP addresses required for routing on Internet.
  8. Was SMTP the only protocol created by Postel?
    No, Postel authored a number of core protocols – TCP transmission control, IPv4 addressing, FTP, Telnet, routing protocols like BGP, and domain name system.
  9. Did Postel receive any recognition during his lifetime?
    Yes, Postel received many acclaims like the IEEE Internet Award, USENIX Lifetime Achievement Award, ICANN Privacy Award for his immense contributions that created the Internet.
  10. What did Postel work on apart from technical RFCs?
    Postel pioneered the IANA organization which coordinates some of the key administrative aspects like IP address allocation crucial for smooth Internet functioning even today.
  11. How is Postel regarded among Internet pioneers?
    Postel is highly revered as being among the most influential engineers whose technical vision and principles largely defined the architecture of the Internet we know today.
  12. Is SMTP still updated to this day?
    Yes, SMTP development continues with new RFCs introduced over time to add functionality like encryption via TLS, authentication, pipelining etc. while retaining Postel’s original design tenets.
  13. What was Postel’s role in the IETF?
    Postel was deeply involved with IETF in maintaining technical standards as the RFC Editor. He also championed the IETF’s open, bottom-up standards process based on collaborative expertise.
  14. Does SMTP follow a client-server or peer-to-peer model?
    Postel chose a client-server model for SMTP with designated mail servers and on-demand mail clients optimized for asynchronous store and forward usage typical for email communications.
  15. How did Postel’s work on TCP/IP aid Internet growth?
    The layered TCP/IP stack allowing inter-networking between diverse physical networks and universal addressing enabled scalable non-centralized growth of the Internet by removing interoperability roadblocks.
  16. Are any key Internet standards not authored by Postel still in use?
    Important examples not created by Postel but still used include HTTP protocol, CIDR IP addressing, IPv6, CSS, public key cryptography standards etc.
  17. Was Postel recognized for his achievements during his lifetime?
    Yes, Postel received many prestigious awards like the IEEE Internet Award and the USENIX Lifetime Achievement Award recognizing his immense contributions to Internet technology.
  18. What aspects of legacy SMTP pose challenges today?
    Lack of authentication and encryption in original SMTP design leads to issues like spam, phishing, snooping etc. necessitating bolt-on extensions like SMTPAuth, TLS, DKIM etc.
  19. Did Postel work alone on the SMTP protocol?
    While Postel is credited as the original author due to RFC 821, some refinements like additional commands were collaborations with other researchers part of the early standards processes.
  20. Are any of the core Internet pioneers who worked alongside Postel still alive?
    Notable Internet pioneers like Vint Cerf, Steve Crocker, Leonard Kleinrock etc. who co-authored many foundational standards alongside Postel still remain active even today more than 50 years later.

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