【正文】 , the server MAY supply the client39。 help to improve the efficiency of access to information。如果簡(jiǎn)單郵件傳輸協(xié)議接收者可以接收郵件則返回OK應(yīng)答。下面討論簡(jiǎn)單郵件傳輸協(xié)議命令和應(yīng)答。進(jìn)程可能直接和其它進(jìn)程通過(guò)已知的IPCE通信。版權(quán)須知版權(quán)所有（1999年）Internet 團(tuán)體，所有權(quán)利將得到保留。討論：認(rèn)證命令顯示了一種和郵件服務(wù)器間的安全認(rèn)證機(jī)制 。如果服務(wù)器接到這樣一個(gè)回應(yīng)，就通過(guò)發(fā)送一個(gè)501的響應(yīng)來(lái)拒絕執(zhí)行認(rèn)證命令。詳細(xì)說(shuō)明這個(gè)SASL側(cè)面的服務(wù)器的名稱(chēng)是“簡(jiǎn)單郵件傳輸協(xié)議”。一個(gè)Base64編碼的字符串通常來(lái)說(shuō)是沒(méi)有長(zhǎng)度限制的。如果認(rèn)證命令的可選的參數(shù)已經(jīng)提供了的話，不管是明確的提出還是由于前面段落的需要，服務(wù)器應(yīng)當(dāng)提供這個(gè)參數(shù)給任何其他支持認(rèn)證擴(kuò)展的用來(lái)中轉(zhuǎn)消息的服務(wù)器。538 請(qǐng)求的認(rèn)證機(jī)制需要加密這個(gè)響應(yīng)碼表示的是所選的認(rèn)證機(jī)制只有在簡(jiǎn)單郵件傳輸協(xié)議連接在需要加密的情況下才能用454 暫時(shí)的認(rèn)證失敗這個(gè)響應(yīng)碼表示的是認(rèn)證失敗的原因是由于服務(wù)器暫時(shí)出現(xiàn)問(wèn)題530 認(rèn)證是必須的除了認(rèn)證，EHLO，HELO，NOOP，RESET或者QUIT這幾個(gè)命令之外的任何一個(gè)命令，都將返回這個(gè)響應(yīng)碼。在SASL商議開(kāi)始之前，任何協(xié)議之間的交互可以暢通無(wú)阻的進(jìn)行，但也有可能被活動(dòng)著的攻擊者修改。（1）它通常只在一個(gè)被信任的范圍里有效（2）它保護(hù)整個(gè)消息的封裝替，而不僅僅是正文（3）它鑒定消息的任務(wù)而不是消息的內(nèi)容（4）在發(fā)信者協(xié)同驗(yàn)證下一個(gè)中轉(zhuǎn)點(diǎn)并且穿越一個(gè)合理的安全層級(jí)的情況下，它可以給發(fā)信者一個(gè)保證，那就是可以把消息安全地傳遞到下一個(gè)地點(diǎn)。Pop全稱(chēng)是郵局協(xié)議，是專(zhuān)門(mén)用于接收郵件的。最后，從系統(tǒng)性能角度分析和設(shè)計(jì)了多種不同的信息過(guò)濾規(guī)則，使系統(tǒng)能夠適應(yīng)不同的應(yīng)用場(chǎng)合，滿足不同的需要。網(wǎng)絡(luò)信息過(guò)濾是根據(jù)一定的標(biāo)準(zhǔn)和利用一定的工具從動(dòng)態(tài)的網(wǎng)絡(luò)信息流中選取相關(guān)信息或剔除無(wú)關(guān)信息的一系列過(guò)程。而且用它的人數(shù)勢(shì)必會(huì)繼續(xù)增加。一個(gè)消息的服務(wù)客戶端可能會(huì)要求用戶通過(guò)驗(yàn)證，在任何它得到一個(gè)合適的SASL的時(shí)候。排在上面的或者下面的被用來(lái)定義為有象征意義的字符串的用處僅僅是為了編輯時(shí)的便利以及清晰。例如：C: 郵件來(lái)源:e=mc2 認(rèn)證=e+3Dmc2S: 250 OK錯(cuò)誤代碼以下的錯(cuò)誤代碼常常用來(lái)描述和標(biāo)識(shí)各種情況。如果服務(wù)器認(rèn)為最初提交消息的地址空間的客戶端是可信任的話，將會(huì)發(fā)出一個(gè)聲明，接著服務(wù)器應(yīng)當(dāng)提供一個(gè)相同的地址空間給任何其他支持認(rèn)證擴(kuò)展的用來(lái)中轉(zhuǎn)消息的服務(wù)器?？蛻舳说腗UST命令將拋棄所有的從服務(wù)器獲得的認(rèn)知，例如不是通過(guò)SASL本身而獲得的簡(jiǎn)單郵件傳輸協(xié)議服務(wù)擴(kuò)展的隊(duì)列。如果客戶端在認(rèn)證機(jī)制的認(rèn)證命令響應(yīng)中使用初始化建議，客戶端就在初始化命令中發(fā)送響應(yīng)的數(shù)據(jù)，服務(wù)器端用535回答來(lái)拒絕認(rèn)證命令。這種認(rèn)證機(jī)制的交互，由一系列的服務(wù)器的響應(yīng)和對(duì)認(rèn)證機(jī)制來(lái)說(shuō)的一些特殊的回答來(lái)組成。諸如MUST, MUST NOT, SHOULD, SHOULD NOT, and MAY這些關(guān)鍵性的單詞被可以看作和“用在RFC文檔中用來(lái)標(biāo)示必須的級(jí)別的關(guān)鍵字” [KEYWORDS]相同的解釋。簡(jiǎn)單郵件傳輸協(xié)議稱(chēng)為簡(jiǎn)單Mail傳輸協(xié)議（Simple Mail Transfer Protocol），目標(biāo)是向用戶提供高效、可靠的郵件傳輸。這種模式也就要求有不同的緩沖區(qū)來(lái)存儲(chǔ)這些對(duì)象，也就是說(shuō)，有一個(gè)回復(fù)路徑緩沖區(qū)，一個(gè)轉(zhuǎn)發(fā)路徑緩沖區(qū)，一個(gè)郵件內(nèi)容緩沖區(qū)。簡(jiǎn)單郵件傳輸協(xié)議命令定義了郵件傳輸或由用戶定義的系統(tǒng)功能。發(fā)送這個(gè)文檔是不受限制的。s body.(3) It authenticates the message submission, not authorship of the message content(4) It can give the sender some assurance the message was delivered to the next hop in the case where the sender mutually authenticates with the next hop and negotiates an appropriate security layer.Additional security considerations are mentioned in the SASL specification [SASL].EMail plays a very important role in modern times. More and more people are using it, and the number of it will larger and larger. Though there are a lot of software for sending and receiving letters such as FoxMail which are also multifunctional, it is difficult and plicated to the Most of people who are curbstone. For this reason, we do this software with the rockbottom protocol of SMTP and Pop. The full name of SMTP is Simple Mail Transfer Protocol. It is used to sending letters. The full name of Pop is Post Office Protocol which is Special to receive letters. I basically take charge to how to realize the function of sending letters. A namespace which is named Mail Send is the soul of my includes two classes. A method named sundial which realize the function step by step belongs to the class of SmtpMail. It detailedly notes the track of client exchange to the server. You can use the software to send either a text E –mail or a texted Email with Attachments. You also can Send a letter to many addressee. In the nature of things, you can use a different SMTP service. The software I did support multiletters and multisender after I test. It is simplier than FoxMail and other professional softwares, but it is easy to hold and use.The rapid development of the Internet has to bee the world39。 second is from one server to another server. SMTP is a request / response protocol, it listen port 25, for receiving the user39。s Mail request to establish with the remote Mail server SMTP connection.Copyright NoticeCopyright (C) the Internet Society (1999). All Rights Reserved.1. IntroductionThis document defines an SMTP service extension [ESMTP] whereby an SMTP client may indicate an authentication mechanism to the server。s most extensive coverage, the largest and most abundant resources of the information network. In the age of the Internet, people share information in the full enjoyment by the convenience of also suffering from information hungry, spam and other problems. How to help users from the Internet access useful information and avoid unhealthy information network pollution has now bee an urgent need for research to solve a problem.Network Information filtering is based on certain standards and the use of certain tools from the dynamic network information flow, select relevant information or omissions of information not related to a series of process. Information filtering technology applications help to reduce pressure on the user39。簡(jiǎn)單郵件傳輸協(xié)議通常有兩種工作模式：發(fā)送簡(jiǎn)單郵件傳輸協(xié)議和接收簡(jiǎn)單郵件傳輸協(xié)議。它的命令是由CRLF結(jié)束的字符串。特定的命令產(chǎn)生自己的緩沖區(qū)，或使一個(gè)或多個(gè)緩沖的內(nèi)容被清除。簡(jiǎn)單郵件傳輸協(xié)議的一個(gè)重要特點(diǎn)是它能夠在傳送中接力傳送郵件，即郵件可以通過(guò)不同網(wǎng)絡(luò)上的主機(jī)接力式傳送。認(rèn)證服務(wù)的擴(kuò)展(1)簡(jiǎn)單郵件傳輸協(xié)議服務(wù)擴(kuò)展的名稱(chēng)是 被動(dòng)認(rèn)證(2)聯(lián)合這個(gè)擴(kuò)展的EHLO關(guān)鍵字的值是“認(rèn)證”(3)認(rèn)證 EHLO關(guān)鍵字 是一個(gè)有空格間隔的被SASL機(jī)制支持的名字列表的參數(shù)(4)一個(gè)新的簡(jiǎn)單郵件傳輸協(xié)議動(dòng)詞“認(rèn)證”定義完成(5)用在關(guān)鍵字“認(rèn)證”的一個(gè)可選的參數(shù)被附加到郵件來(lái)源命令里，用來(lái)指定郵件來(lái)源命令一行的最大長(zhǎng)度不能超過(guò)500個(gè)字符(6) 此擴(kuò)展和委托協(xié)議兼容認(rèn)證