SMTP Inside Out

by Heinz Tschabitscher

Iko maIndaneti inoshanda sei

Wati wambozvibvunza here zvinoitika kana iwe ukanyora bhodhi Send mumapurogiramu yako e-email? Zvichida kwete, ndinofungidzira - chero bedzi inoshanda. Ichi ndicho chikonzero chikonzero nei iwe uchifanira kushamisika, zvakadaro. Kana pane chimwe chinhu chisiri kushanda zvakanaka kuti uzive zvisingashande. Kazhinji, iyo hafu ndiyo mhinduro.

Paunotumira email SMTP inowanikwa. SMTP inononoka kune Simple Mail Transfer Protocol sezvinotsanangurwa muRFC 5321: Simple Mail Transfer Protocol. Tsamba yako muteereri anotumira hurukuro kumushandi we SMTP uchishandisa nzira iyi yakachena uye iri nyore kuwana email kubva kune imwe nzvimbo kune imwe.

The Flirt

Purogiramu yako ye email inova SMTP maklayiti , inobatanidza kumafaira 25 e- mail yako server (kazhinji kamba ye SMTP ) uye - inoti EHLO . Makombiyuta, pakuguma, ari vanhu chete uye chii chinokosha ndechokuti inoda kuva nehanya. Kutaura zvazviri, hazviedzi kuve nekuremekedza asi kushandisa zvishoma zvakare kuwedzera kune SMTP iyo yakaunza mavhiri maviri emurairo HELO huri mberi (mutemo we SMTP unowanzo uine mavara mana).

Flavored Two HELO

EHLO, kuva yakanyanya kuitika kunoita kuti server ibudise zvimwe zvose zvinowanikwa (zvakadai sekuzivisa chiitiko chekuzivisa kana kukwanisa kutakura mameseji ane zvimwe kunze kwemashoko ASCII akachengeteka) inotsigira.

Kwete sevha rese inobvumira kubvumirana uku, asi inobvumirwa kubvuma HELO yakajeka iyo inofunga kuti hapana zvimwe zvayo zviripo. Zvose mabhero anorayira zvinoda kuti muteresi ataure nzvimbo yake pashure pe ** LO, zvisinei. Mukuita, izvi zvinotarisa chimwe chinhu chakadai:

220 mail.domain.net ESMTP Server
HELO
501 HELO inoda nzvimbo yekero
HELO localhost
250 mail.domain.net Hello localhost [127.0.0.1], anofara kukuonana newe

(Zvandinowedzera zviri mumatariki , maserivha ekubuda ari madema; mitsara inotanga ne5 inoratidza kukanganisa .)

The Sender

Izvo zvakasara zveprotocol zvinokodzera zvakakosha zvayo. Kana iwe uchida kutumira email, unotanga nemamwe mazita MAIL FROM:. Kutevera izvi kunouya kero ye email yeanotumira, sezvinoratidzwa neyo kubva. Usakanganwa kuisa mabheji akakomberedza kero, kunyange (se ). Kuenderera mberi nemuenzaniso wedu, tine:

MAIL FROM:
250 sender@example.com ... Sender ok

Munhu anogamuchira

Mushure mekunge sevha yakagamuchira kero yekutumira, muteresi anogona kupa kero yemupiki. Murairo wechiito ichi, RCPT TO: zvakare pane kufungidzira. Ndinoda kutumira tsamba kwandiri :

RCPT TO: recipient@example.com
250 support@lifewireguide.com ... Muteveri ok (iyo mutsara)

Izvo sevha ichaita mutsara zvinoreva izvo chete: iyo ichachengetedza mail mukati memunharaunda uye yoitumira pamwe chete nemamwe mavhesi akambomira mukati-kati (semuenzaniso, maminetsi makumi matatu oga oga). Iyi maitiro inobva mukugadzirisa uye server inogonawo kutumira tsamba panguva iyoyo.

Tava kuda kupera. Chinochiriko, asi, chikamu chinokosha: mharidzo chaiye.

The Message

Iye zvino kuti "envelope" yakapedzwa, dhesi yemutumwa wekutevera sezvaanogona kutevera. Iyi "deta" inoumba muviri we imeyeri pamwe nemusoro wemisoro .

Mutemo wokutanga nyika inoita kuti seva agamuchire mharidzo iyi DATA . Kutevera izvi ndeye mamiriro ekutanga emishumo ye email uye zvino muviri, zvose zvinogadzira imwechete huru bhokisi remashoko (kana deta). Kutaurira sevha kuti mhinduro yakapedzisa dot pane mutsara pachayo inoshandiswa (\ r \ n. \ R \ n). Saka ndinotumira shoko rangu:

DATA
354 Isa mail, kuguma ne "." pamutsara pachawo
Mharidzo-Mutsamba:
Zuva: Zuva, 17 Aug 1997 18:48:15 +0200
Kubva: Heinz Tschabitscher
Kuna: Heinz Tschabitscher
Nyaya: Pamusangano we Summarize-Proust

Kunoenda kuNyika Yenyika!
.
250 SAA19153 Mharidzo yakagamuchirwa nokuda kwekutumira

Hongu, izvi zvinoreva kuti iwe unogona kutaura zita zvakasiyana zvachose neyeyo email inopinda kune: Kumunda. Semuenzaniso, unogona kushandisa "Zita rekubvuma rinopedzwa" .

Magumo

Iwe zvino unogona kutumira ma email akawanda sezvaunoshuva kudzokorora matanho kubva MAIL FROM: kusvika . . Kana iwe waita izvi, iwe unogona kusiya sevha nemutemo we QUIT uye ndizvo zvatinoita chete:

QUIT
221 Zvakanaka

Ndingaita sei Izvi?

Chinhu chisina kunyanya kukosha ndechokuti terenet kune yakashambadzira mail server (unogona kuwana kero yaro mumigodhi yekombikiti yako yekombiyuta ) pachiteshi 25.

Vhura mutemo wekuraira.
Tora "telnet 25".
Taura nes server uchishandisa SMTP.

Nzira iri nyore kushandisa iyi Java applet , iyo inoedza kutevedzera SMTP protocol uye inokutungamirira iwe kuburikidza nehurukuro.