RFC 1957

Some Observations on Implementations of the Post Office Protocol (POP3)

📅 published June 1996, from ietf

RFC 1957: Some Observations on Implementations of the Post Office Protocol (POP3) 🎀

okay bestie, this one is from Russell Nelson at Crynwr Software 💅, dated June 1996, and it's part of the Network Working Group 🧚. It's labelled Informational, which is giving "here are some vibes, not a rule" ✨. It updates RFC 1939 (that's the POP3 spec itself, "Post Office Protocol - Version 3") 📮. It doesn't list anything it obsoletes. let's get into it 🦋

Status of this Memo 📜

so this memo gives info to the Internet community 🌸. It does not specify an Internet standard of any kind, so it's not a standard, no cap 🙈. Distribution of this memo is unlimited, so share it with the whole group chat 💜.

Observations 👀

Sometimes an implementation gets mistaken for a standard 💀. POP3 servers and clients are no exception, bestie.

The widely-used UCB POP3 server, popper, which Qualcomm has been further developing 🔥, always has extra information after the status indicator. So the status indicator always has a space after it ✨. Two POP3 clients have been observed to expect that space, and they fail when it isn't there 😭. The RFC does not require the space, hence this memo 💅.

Those two clients are the freely copyable Unix "popclient" and the proprietary "netApp Systems Internet Series" 🫶. The authors of both have been contacted, and new releases will not expect the space. Old versions should still 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 hasn't achieved wide penetration yet 🌈. Newer versions of the Qualcomm POP server implement it. Known client implementations of APOP include the GNU Emacs VM client, Eudora Lite, and Eudora Pro 🍓.

Security Considerations 🔒

🚨 Security issues are not discussed in this memo. 💀

References 📚

[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
EMail: nelson@crynwr.com
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