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Some Observations on Implementations of the Post Office Protocol (POP3) (RFC1957) Disclosure Number: IPCOM000004182D
Original Publication Date: 1996-Jun-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 2 page(s) / 2K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

R. Nelson: AUTHOR


Status of this Memo

This text was extracted from a ASCII document.
This is the abbreviated version, containing approximately 100% of the total text.

Network Working Group R. Nelson

Request for Comments: 1957 Crynwr Software

Updates: 1939 June 1996

Category: Informational

Some Observations on Implementations

of the Post Office Protocol (POP3)

Status of this Memo

This memo provides information for the Internet community. This memo

does not specify an Internet standard of any kind. Distribution of

this memo is unlimited.


Sometimes an implementation is mistaken for a standard. POP3 servers

and clients are no exception. The widely-used UCB POP3 server,

popper, which has been further developed by Qualcomm, always has

additional information following the status indicator. So, the

status indicator always has a space following it. Two POP3 clients

have been observed to expect that space, and fail when it has not

been found. The RFC does not require the space, hence this memo.

These clients are the freely copyable Unix "popclient" and the

proprietary "netApp Systems Internet Series". The authors of both of

these have been contacted, and new releases will not expect the

space, but old versions should be supported.

In addition, two popular clients require optional parts of the RFC.

Netscape requires UIDL, and Eudora requires TOP.

The optional APOP authentication command has not achieved wide

penetration yet. Newer versions of the Qualcomm POP server implement

it. Known client implementations of APOP include GNU Emacs VM client

and Eudora Lite and Eudora Pro.

Security Considerations

Security issues are not discussed in this memo.


[1] Myers, J., and M. Rose, "Post Office Protocol - Version 3",

STD 53, RFC 1939, May 1996.

Author's Address

Russell Nelson

Crynwr Software

521 Pleasant Valley Rd.

Potsdam, NY 13676

Phone: +1.315.268.1925

FAX: +1.315.268.9201