RFC 1426 · PROPOSED STANDARD · 1993
SUN · 14 JUN 2026
SMTP Service Extension for 8bit-MIMEtransport
Overview
RFC 1426, “SMTP Service Extension for 8bit-MIMEtransport”, is a Proposed Standard document published in February 1993 by J. Klensin, N. Freed, M. Rose, E. Stefferud, D. Crocker. It has been obsoleted by RFC 1652 — refer to the newer document for the authoritative version. The canonical text is published by the RFC Editor.
Abstract
This memo defines an extension to the SMTP service whereby an SMTP content body containing octets outside of the US ASCII octet range (hex 00-7F) may be relayed using SMTP.
What “Proposed Standard” means
An entry-level standards-track specification: stable, peer-reviewed and a solid basis for implementation, though it may still evolve before becoming an Internet Standard.
Read this RFC
The canonical text of RFC 1426 is hosted at rfc-editor.org. Available in TXT,HTML.
Relationships to other RFCs
Other RFCs from 1993
- RFC 1425 SMTP Service Extensions
- RFC 1427 SMTP Service Extension for Message Size Declaration
- RFC 1424 Privacy Enhancement for Internet Electronic Mail: Part IV: Key Certification and Related Services
- RFC 1428 Transition of Internet Mail from Just-Send-8 to 8bit-SMTP/MIME
- RFC 1423 Privacy Enhancement for Internet Electronic Mail: Part III: Algorithms, Modes, and Identifiers
- RFC 1429 Listserv Distribute Protocol
- RFC 1422 Privacy Enhancement for Internet Electronic Mail: Part II: Certificate-Based Key Management
- RFC 1430 A Strategic Plan for Deploying an Internet X.500 Directory Service