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Survey of SMTP implementations (RFC0876) Disclosure Number: IPCOM000003925D
Original Publication Date: 1983-Sep-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 13 page(s) / 38K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

D. Smallberg: AUTHOR



This text was extracted from a ASCII document.
This is the abbreviated version, containing approximately 7% of the total text.

Network Working Group D. Smallberg

Request for Comments: 876 ISI

September 1983

Survey of SMTP Implementations


This memo is a survey of implementation status. It does not specify an

official protocol, but rather notes the status of impementation of

aspects of a protocol. It is expected that the status of the hosts

reported on will change. This information must be treated as a snapshot

of the state of these implementations.


From May to August 1983, I tested SMTP servers on the Internet to

see whether they accepted connections from the Arpanet (a Class A

network) and ISI-Net (a Class B network), whether they accepted the user

"postmaster" as a mail recipient, and whether a nonexistent user was

immediately rejected as a mail recipient.

The hosts from which the tests were conducted were ISI-VAXA on the

Arpanet (running 4.1bsd UNIX), and ISI-MOE on ISI-Net (running 4.1a).

Internet hosts were tested at various times throughout the last four

months. During the survey, I noted anomalies in a few dozen hosts' SMTP

servers; examples included a RSET command causing the server to close

the connection, a VRFY POSTMASTER evoking a reply containing an illegal

mailbox, and some cases of improper reply codes. These bugs were

reported and in most cases promptly fixed.

I would class three problems as significant because about 40 hosts

exhibit at least one of them:

1) In reply to a RSET and/or a NOOP command, some servers reply

"200", which is never a legal reply code, instead of "250".

(See sections 4.2 and 4.3 of RFC 821.)

2) If a VRFY command occurs before a MAIL command, some hosts

reply "554 Nested MAIL command". The end of section 4.1.1 of

RFC 821 states that a VRFY may occur anywhere in the session.

3) If a mail transaction is started, with a sender and receiver

specified, and a RSET is issued before the text of the message

itself is collected, some servers send a message to the sender

about being unable to deliver mail because no message was

collected. While RFC 821 doesn't rule this out, it certainly

is not consistent with the notion of resetting the transaction.

In the table in the appendix, the names and addresses of the hosts

tested were taken from the NIC host table of 17 August 1983. TACs and

echo hosts were not included in the survey.

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RFC 876

Here are the summarized res...