I-Protocol ye-Mail Transfer Simple (SMTP) iyinqubo yokuxhumana ejwayelekile yokuthumela imilayezo ye-imeyli kumanethiwekhi webhizinisi kanye ne-inthanethi. I-SMTP yasungulwa ekuqaleni kwawo-1980 futhi ihlala enye yezinhlelo ezithandwa kakhulu emhlabeni jikelele.
Isofthiwe ye-imeyili ngokuvamile isebenzisa i-SMTP yokuthumela noma i-Post Office Protocol 3 (POP3) noma i-Internet Message Access Protocol (IMAP) yokuthola i-imeyili. Naphezu kweminyaka yobudala, akukho okunye okungokoqobo ku-SMTP ekhona ekusetshenzisweni okujwayelekile.
Indlela SMTP isebenza ngayo
Zonke izinhlelo zamaklayenti zanamuhla zisekela i-SMTP. Amasethingi we-SMTP agcinwe kwiklayenti le-imeyili afaka ikheli le-IP yesiphakeli se-SMTP (kanye namakheli we-POP noma i-IMAP iseva ukuthola ama-imeyili). Amaklayenti asekelwe ku-inthanethi afaka ikheli le-SMTP iseva ngaphakathi kokucushwa kwabo, kuyilapho amaklayenti e-PC anikeza izilungiselelo ze-SMTP ezivumela abasebenzisi ukuthi bacacise iseva yabo yokuzikhethela.
Iseva ye-SMTP engokwenyama ingazinikezelwa ekusebenzeni imoto ye-imeyili kuphela kepha ngokuvamile ivame ukuhlanganiswa okungenani ne-POP3 futhi ngezinye izikhathi neminye imisebenzi yeseva ye-proxy .
I-SMTP isebenza phezulu kwe- TCP / IP futhi isebenzisa inombolo ye- TCP port 25 yokuxhumana okujwayelekile. Ukuze uthuthukise i-SMTP futhi usize ukulwa nogaxekile ku-intanethi, amaqembu amazinga abuye akhethe i-port ye-TCP 587 ukusekela izici ezithile ze-protocol. Amasevisi we-imeyli ambalwa we-Web, njenge-Gmail, sebenzisa i-port ye-TCP engavumelekile ye-465 ye-SMTP.
Imiyalo ye-SMTP
Inombolo ye-SMTP ichaza isethi yemiyalo - amagama ezinhlobo ezithile zemilayezo ezithumela amakhasimende kwiseva yeposi lapho ecela ulwazi. Imiyalo evame ukusetshenziswa kakhulu yilezi:
- I- HELO ne- EHLO - imiyalo eqala iseshini entsha yeprotocol phakathi kwamakhasimende nesiphakeli. Umyalo we-EHLO ubacela ukuthi baphendule nganoma yikuphi ukukhuliswa kwe-SMTP okuzikhethela okusekelayo
- MAIL - umyalo wokuqalisa ukuthumela umlayezo we-imeyli
- Umyalo we- RCPT wokunikeza ikheli elilodwa le-imeyili lomamukeli womlayezo wamanje olungiselelwe
- I-DATA - umyalo obonisa ukuqala kokudluliselwa komlayezo we-imeyili. Lo myalo uqala uchungechunge lwemiyalezo eyodwa noma ngaphezulu okulandelayo okuqukethe isici somlayezo. Umlayezo wokugcina wokulandelana awunalutho (oqukethe kuphela isikhathi (.) Njengesigqi sokuqeda) ukukhombisa ukuphela kwe-imeyili.
- I-RSET - ngenkathi inqubo yokuthumela i-imeyili (ngemva kokukhipha umyalo we-MAIL), noma ukuphela kokuxhumeka kwe-SMTP kungasetha kabusha uxhumano uma kuhlangana nephutha
- I-NOOP - umlayezo ongenalutho ("akukho osebenzayo") owenzelwe njengenhlobo ye- ping ukuhlola ukuphendula komunye umkhawulo weseshini
- I-QUIT - inqamula iseshini yeprotocol
Umamukeli wale miyalo uphendula ngempumelelo noma izinombolo zekhodi yokuhluleka.
Izinkinga nge-SMTP
I-SMTP ayinakho izici zokuphepha ezakhelwe ngaphakathi. Abakwa-spammers be-inthanethi banikwe amandla ukuxhaphaza i-SNMP esikhathini esidlule ngokudala inani elikhulu le-imeyili elingenayo i-junk futhi bezithunyelwa ngamaseva e-SMTP avulekile. Isivikelo ngokumelene nogaxekile sithuthukile eminyakeni edlule kodwa asiyizikhohlisi. Ukwengeza, i-SMTP ayivimbeli abagaxekile ekubekeni (nge-MAIL umyalo) fake "Kusuka:" amakheli e-imeyli.