Thola ukuthi i-DSN ihlose kanjani ukwethula isimo sokuletha kwi-imeyili ye-SMTP.
Wake Wangazibuza Kwenzeka Kanjani I-imeyili Othumele?
Ngisho nje ukubuka okufushane mayelana ne- SMTP protocol uzobe uqaphele ukuthi ngaphandle kwe-HELO evamile, kune-EHLO, okwenza iseva elwandisiwe le-SMTP lithengise amakhono alo ngaphesheya kwezinga lokuqala. Enye yalezi yi-DSN. I-DSN? Ingabe i-DNA ne-DDT ayanele?
Ukuphikisa ukuthi i-imeyili ayithembekile, ukuthi umuntu kufanele " ... ukondla iseva yabo kangcono; idle i-mail yami ... " akuvamile. Ngikwenza ngokwami. Noma kunjalo, asikho isizathu esiningi sokusekela lezi zinsolo.
I-Delivery S tatus I-otification isivele isukela ku-RFC 821 (kusukela ngo-1982). Ngokushesha lapho ingxenye ye-DATA yenqubo ye- SMTP isiphelile futhi iseva yamukele i-imeyili yokulethwa yiyona enesibopho sayo. Uma, nganoma yisiphi isizathu, asikwazi ukuyifinyelela kumamukeli kufanele ayibuyisele emuva ngesaziso sephutha kumthumeli wangempela. Lokhu kwabangela enye i- imeyili engafihlekile.
Ngaphandle kwalokhu, lo mhlangano omdala wawusho ukuthi noma ngabe unomyalezo wephutha noma awutholanga lutho lapho ungasazi lutho : i-imeyili kungenzeka ukuthi ifike noma kungenzeka. Imilayezo yesiphambeko ezimweni eziningi yayiyusizo nje njengoba kungekho myalezo wephutha. Njengoba i-imeyili iba ngaphezulu nakakhulu lokhu akukwanelisi (njengokungathi kwakungaphambili).
Izandiso ze-DSN ku-SMTP
I-RFC 1891 iphakamisa ezinye izandiso kwinqubo ye- SMTP okufanele ibangele isistimu ye-DSN ethembeke futhi esebenzayo. Kuyinto isethi yezandiso kumyalo we-MAIL ne-RCPT (uma lokhu kungasho lutho kuwe, funda ukuthi i-SMTP isebenza kanjani bese ubuya lapha.).
Ayikho i-EHLO, Awukho Okujabulisayo
Okokuqala, kufanele siqiniseke ukuthi iseva isekela i-DSN. Ngakho-ke, kufanele sisho i-ELO futhi silalelisise. Uma iphendula nge-DSN ngenye indlela ohlwini lwamasu singacabanga ukuthi lizokwazi ukukhonza izicelo zethu. Uma kungenjalo, akunjalo: singazama enye iseva noma sivele sibuyele ku- imeyili ngaphandle kwe-DSN. Isibonelo (ukungena kwami kuluhlaza okwesibhakabhaka, ukukhishwa kweseva kumnyama):
220 larose.magnet.at ESMTP Sendmail 8.8.6 / 8.8.6; Ilanga, 24 Aug 1997 18:23:22 +0200
EHLO localhost
I-250-larose.magnet.at Sawubona wangakini [127.0.0.1], ujabulele ukukuhlangabeza
250-EXPN
250-VERB
250-8BITMIME
250-SIZE
250-DSN
250-ONEX
250-ETRN
250-XUSR
250 HELP
Ngenhlanhla, phakathi kwezinye izinto sithola i-DSN.
Izandiso ze-DSN Sender
Umyalo olandelayo ngokuvamile u-MAIL FROM :. Nge-DSN, lokhu akufani. Kodwa kunezinketho ezimbili ezengeziwe ongayikhipha: RET no-ENVID.
Ikhetho le-RET labekwe esikhundleni sokungena ngokungahambisani emyalweni we-MAIL, kodwa lihambisana lapha kanye nanoma ikuphi. Inhloso ukucacisa ukuthi umlayezo wakho wangempela kufanele ubuyiselwe kanjani uma kwenzeka ukwehluleka kwezidingo. Iziphakamiso ezivumelekile zigcwele ne-HDRS. Okokuqala kusho ukuthi umlayezo ophelele kufanele ufakwe emlayezo wephutha, i-HDRS iyala iseva ukuthi ibuyisele kuphela izinhloko ze-imeyili ehlulekile. Uma i-RET ingacacisiwe, iseva kuseva okumele ukwenze. Ezimweni eziningi i-HDRS izoba yinani elizenzakalelayo.
I-ENVID impela ingowomthumeli njengoba yena noma (kunalokho) iklayenti lakhe le-imeyili kuyoba yedwa eyenza lesi sihlonzi semvilophu . Inhloso yalo ukutshela umthumeli ukuthi iyiphi i-imeyili umlayezo wephutha okhishwe ngokungafani. Ifomethi ye-ID ngokuyisisekelo ishiya emcabangweni womthumeli. Ngeke sisebenzise i-ENVID kusibonelo sethu (umcabango!):
MAIL KUSUKA: sender@example.com RET = HDRS
250 sender@example.com ... Umthumeli ok
Ngokusobala, sifuna kuphela ukubuyisela ama-header ku-DSN yethu.
Izandiso ze-DSN Abamukeli
I-RCPT TO: ithola ukwabelana kwayo okuhle kwezandiso kanye: QAPHELA futhi u-ORCPT.
QAPHELA ukuthi inhliziyo yangempela ye-DSN. It utshela iseva lapho ukuthumela isaziso isimo isimo. I-value yokuqala engaba yiyo noma yikuphi okusho ukuthi ngaphansi kwanoma yiziphi izimo i-DSN kumele ibuyiselwe kumthumeli. Lokhu kwakungenakwenzeka ngaphandle kwe-DSN. Khona-ke kukhona i-SUCCESS, ezokwazisa uma i-imeyili yakho ifakwe lapho iya khona. I-FAILURE ingumlingani we-SUCCESS (!): I-DSN izofika uma kukhona ukuphikisana okwenzeka ngesikhathi sokubeletha. Okukhethwa kukho kokugcina yi-DELAY: uzokwaziswa uma kunokulibaziseka okungavamile kokulethwa, kepha imiphumela yokuletha yangempela (impumelelo noma ukwehluleka) ayinqunyiwe. Akufanele kube yilokho kuphela ukuphikisana uma kuchaziwe, ezinye ezintathu zingase zivele kuhlu, zihlukaniswe yi-comma. UKUHLELA NOKUPHILA kwakha iqembu elihle kakhulu ndawonye (!), Ekutsheleni (cishe) noma yikuphi okwenzekayo ngeposi lakho.
Inhloso ye-ORCPT ukugcina umamukeli wangempela womlayezo we-imeyli, isibonelo uma ithunyelwa kwenye ikheli. Impikiswano yalolu khetho ikheli le-imeyili lomamukeli wangempela kanye nohlobo lwekheli. Uhlobo lwekheli luza kuqala, lulandelwa i-semicolon futhi ekugcineni ikheli. Ngokwesibonelo:
I-RCPT KU: support@example.com NOTIFY = FAILURE, DELAY ORCPT = rfc822; support@example.com
250 support@example.com ... Umamukeli ok (uzobe umgqeni)
Lokhu kulandelwa yi-DATA njengoba siyazi futhi ekugcineni, ngethemba, isaziso sesimo sokuthumela ukukwazisa ngempumelelo.
Ingabe i-DSN isebenza?
Yiqiniso, konke lokhu ubuhle kanye nobufakazi buzosebenza kuphela uma izithunywa zezokuthutha zeposi zisuka kumthumeli zisekela i-DSN ukwesekwa. Ngolunye usuku bayokwenza.