📄 rfc876.txt
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Network Working Group D. SmallbergRequest for Comments: 876 ISI September 1983 Survey of SMTP Implementations ---------------------- This memo is a survey of implementation status. It does not specify anofficial protocol, but rather notes the status of impementation of aspects of a protocol. It is expected that the status of the hostsreported on will change. This information must be treated as a snapshotof the state of these implementations. ---------------------- From May to August 1983, I tested SMTP servers on the Internet tosee whether they accepted connections from the Arpanet (a Class Anetwork) and ISI-Net (a Class B network), whether they accepted the user"postmaster" as a mail recipient, and whether a nonexistent user wasimmediately rejected as a mail recipient. The hosts from which the tests were conducted were ISI-VAXA on theArpanet (running 4.1bsd UNIX), and ISI-MOE on ISI-Net (running 4.1a).Internet hosts were tested at various times throughout the last fourmonths. During the survey, I noted anomalies in a few dozen hosts' SMTPservers; examples included a RSET command causing the server to closethe connection, a VRFY POSTMASTER evoking a reply containing an illegalmailbox, and some cases of improper reply codes. These bugs werereported and in most cases promptly fixed. I would class three problems as significant because about 40 hostsexhibit 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 hoststested were taken from the NIC host table of 17 August 1983. TACs andecho hosts were not included in the survey.Page 1 RFC 876 Here are the summarized results of the survey:483 hosts were tested283 are claimed by the host table to support SMTP 49 of those 283 (17%) failed to permit a connection to be opened from either ISI-VAXA or ISI-MOE. 51 hosts did not claim to support SMTP, but did allow a connection to be opened from at least one of the two ISI test hosts.285 hosts were connected to from ISI-VAXA170 hosts were connected to from ISI-MOE; all 170 were connected to from ISI-VAXA as well.115 hosts out of the 285 (40%), therefore, could be connected to from ISI-VAXA only. 69 of the 285 connectable hosts (24%) returned a positive reply to the command "VRFY postmaster"162 hosts out of the 285 connectable hosts (57%) immediately rejected mail addressed to a nonexistent user; that is, they gave an "unknown user" reply to the command "RCPT TO:<jqkxwzvb@host>", where "host" was the foreign host.115 hosts out of the 285 (40%) gave a positive acknowledgement to a RCPT command with a nonexistent user. 8 hosts (3%) were never up during this part of the test.121 hosts out of the 162 which immediately reject mail to nonexistent users (75%) accepted mail for the recipient "postmaster". Thus, 42% (121 out of 285) of the connectable hosts do not immediately reject mail for "postmaster".References:RFC 821 Postel, J., "Simple Mail Transfer Protocol", RFC 821, Network Information Center, SRI International, Menlo Park, August 1982.Page 2 RFC 876 APPENDIX The hosts in this table are taken from the NIC host table of17 August 1983, with TACs and echo hosts omitted, and are grouped bynetwork. There are six result entries for each host:Claim SMTP + = the host table lists this host as supporting SMTP; - = such support is not listedArpanet + = a connection could be opened from ISI-VAXA - = no such connection could be openedISI-Net + = a connection could be opened from ISI-MOE - = no such connection could be openedVRFY Post + = the command "VRFY postmaster" evoked a positive reply - = it did notRCPT Post + = the command "RCPT TO:<postmaster@host>" elicited a positive reply - = it did notBad jqkx + = the command "RCPT TO:<jqkxwzvb@host>" elicited a negative reply (i.e. unknown user) - = it received a positive reply (i.e. recipient accepted)Claim Arpa ISI- VRFY RCPT BadSMTP net Net Post Post jqkx Host name Address Notes----- ---- ---- ---- ---- ---- --------- ------- ----- - - - - - - alta-coma 3.1.0.50 - - - - - - satnet 4.0.0.0 - - - - - - etam-expak 4.0.0.1 - - - - - - goonhilly-expak 4.0.0.2 - - - - - - tanum-expak 4.0.0.3 - - - - - - satnet-sink 4.0.0.37 - - - - - - etam-monitor 4.0.0.41 - - - - - - goonhilly-monitor 4.0.0.42 - - - - - - tanum-monitor 4.0.0.43 - - - - - - raisting 4.0.0.72 - - - - - - raisting-monitor 4.0.0.78 - - - - - - raisting-expak 4.0.0.79 - - - - - - fucino 4.0.0.88 - - - - - - fucino-monitor 4.0.0.94 - - - - - - fucino-expak 4.0.0.95 + + + - + + bbncca 8.0.0.2 + + + - + + bbnccb 8.1.0.2 + + + - + + bbnccc 8.2.0.2 + + + - + + bbnccd 8.3.0.2 + + - - + - bbnccg 8.0.0.3 b + + + - + + bbnccf 8.0.0.4Page 3 RFC 876Claim Arpa ISI- VRFY RCPT BadSMTP net Net Post Post jqkx Host name Address Notes----- ---- ---- ---- ---- ---- --------- ------- ----- + + + - + + bbnccp 8.2.0.4 + + + - + + bbncci 8.3.0.4 + + + - + + bbnh 8.4.0.4 + - - - - - bbn-cdnoc 8.0.0.5 + + + - + + bbn-cd 8.1.0.5 + + + - + + bbn-admin 8.1.0.6 + + + - + + bbn-inoc 8.2.0.6 + + + - + + bbnccw 8.3.0.6 + + + - + + bbnccs 8.0.0.7 + + + - + + bbnz 8.1.0.7 + + + - + + bbnccq 8.2.0.7 + + + - + + bbnccx 8.0.0.8 + + + - + + bbnccy 8.2.0.8 + + + - + + csnet-cic 8.0.0.14 + + + - + + bbn-noc 8.1.0.14 + + + - + - ucla-cs 10.0.0.1 - - - - - - ucla-ccn 10.1.0.1 + + + - + - ucla-locus 10.2.0.1 + + + - + - ucla-ats 10.3.0.1 - - - - - - sri-nsc11 10.0.0.2 + + + + + + sri-kl 10.1.0.2 + + + - + - sri-csl 10.2.0.2 + + - - + + sri-tsc 10.3.0.2 + + + - + - nosc-cc 10.0.0.3 - - - - - - logicon 10.2.0.3 + + + - + - nprdc 10.3.0.3 + + + + + + utah-cs 10.0.0.4 + + + - + - utah-20 10.3.0.4 + + + - + - bbnf 10.0.0.5 + + + - + - bbng 10.1.0.5 + + + - + - bbna 10.3.0.5 + + + + + + mit-multics 10.0.0.6 + + + - + - mit-dms 10.1.0.6 - - - - - - mit-ai-reserved 10.2.0.6 + + + - + - mit-ml 10.3.0.6 + + + + + - rand-relay 10.1.0.7 + + + - + + rand-unix 10.3.0.7 + + + - + + nrl 10.0.0.8 + + + - + - nrl-aic 10.1.0.8 + + + - + + nswc-wo 10.2.0.8 - - - - - - nrl-tops10 10.3.0.8 - - - - - - nrl-arctan 10.6.0.8 + + + - + - nrl-css 10.7.0.8 - - - - - - harv-10 10.0.0.9 + + + - + - yale 10.2.0.9 + + + - + + ll 10.0.0.10 + + + - + - ll-vlsi 10.1.0.10 + + - - - + ll-xn 10.2.0.10 + + - - - + ll-en 10.4.0.10 + - - - - - ll-sst 10.6.0.10Page 4 RFC 876Claim Arpa ISI- VRFY RCPT BadSMTP net Net Post Post jqkx Host name Address Notes----- ---- ---- ---- ---- ---- --------- ------- ----- + + + - + + su-ai 10.0.0.11 + + + + + + su-score 10.3.0.11 + + + - + + compion-vms 10.0.0.12 + + + + + + gunter-adam 10.1.0.13 - + + - + - cmu-cs-b 10.0.0.14 + + + - + - cmu-cs-a 10.1.0.14 + + + - + - cmu-cs-c 10.3.0.14 + + + + + - rochester 10.0.0.15 + + + - + + ames-tss 10.0.0.16 + + + - - + ames-vmsa 10.2.0.16 - + + - - + ames-vmsb 10.3.0.16 + + + - + + mitre 10.0.0.17 - + + - - + mitre-gateway 10.1.0.17 - - - - - - mitre-lan 10.4.0.17 + + + + + + radc-multics 10.0.0.18⌨️ 快捷键说明
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