Which protocol is used when sending files as attachments?
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MIME stands for Multipurpose Internet Mail Extensions. MIME extends the text-oriented basic Internet email system, allowing binary attachments in emails. Show
MIME emails are normal Internet text emails, which are composed of headers and formatted message contents that conform to RFC 2822/5322. For more information about RFC addresses in the MIME protocol, click here. MIME messagesA common text-based email is comprised of a header including From, To, Subject, and content. Generally, the content is either a single-part, such as text, image, audio, video, application, or multipart. The header and content are separated with a space, and the type of the body is described by the header Content-Type.
Domain Name Meaning Received Transfer path Return-Path Reply address Delivered-To Sending address Reply-To Reply address From The sender address To The recipient address Cc Carbon copy address Bcc Blind carbon copy address Date Date and time Subject Subject Message-ID Message ID MIME-Version MIME version Content-Type Content type Content-Transfer-Encoding Content transfer encoding
MIME email body
The meanings of section headers are explained in the following table: Domain Name Meaning Content-Type Content type Content-Transfer-Encoding Content transfer encoding Content-Disposition Content disposition Content-ID Content ID Content-Location Content location (path) Content-Base Content base Three common multipart types are multipart/mixed, multipart/related, and multipart/alternative. A sample graph of complex type hierarchy is shown as follows: Child sections within the content of multipart types are defined by the boundary parameter string specified in headers. All child sections start with -boundary, while parent sections end with -boundary-. Sections are separated with spaces.
The total size of attachment mail shall not exceed 15m, and the maximum number of attachments at a time shall not exceed 100.Supplementary note: 15MB refers to the actual total size of SMTP email. Since the base64 encoded email code will expand by more than 1.5 times, the total size is not the size seen on the customer side. It is recommended to prepare according to 8MB for attachment restrictions. If you need to send large attachments, it is recommended to add hyperlinks to the content. DEFINITION File transfer protocol is a standardized method for sending unencoded binary files over IP connections. FTPing a file is more reliable than other methods, such as sending it as an attachment to an e-mail. The sending computer breaks the file data into numbered packets. The receiving computer uses the numbers to reassemble the packets in the right order.By Sami Lais Computerworld| FTP, developed in 1969 by the Department of Defense's Defense Advanced Research Projects Agency, is a standard for moving files across IP-based networks such as the Internet. Based on the TCP/IP protocol, FTP is platform-independent, which makes it possible for different computers running different operating systems to exchange files. SometimeOld Ways Are Best More than 30 years after it was developed, FTP is still the most efficient way to download large files over the Internet. Want a map that shows the habitat of every vertebrate and plant, as well as the latitude, longitude, elevation, rainfall, temperature range and climate of the Grand Canyon? The U.S. Geological Survey (USGS) in Tucson, Ariz., uses a single Unix box to provide the data sets that create such multilayer maps and then FTPs the final map to the requesting computer. Why does the USGS use FTP? There are several reasons: Text files are, by default, sent in ASCII format. The client, or sending computer, converts the data into 8-bit ASCII format. The server, or receiving computer, converts the ASCII text into a format appropriate to its hardware and operating system. Images and other nontext data such as compiled programs are sent as binary data, using 8-bit bytes. Typically, FTP files are compressed. They can be self-extracting, or you may need to use a program such as PKZIP to uncompress them. A user contacts a server via the FTP client, establishes a connection, logs on to the network, requests directory listings and copies files. This can be done by typing commands or via an FTP utility running under a graphical user interface such as Windows. Rules of Engagement One variation of FTP is Trivial FTP, which has no directory or password capabilities. However, the most popular form is Anonymous FTP, which is dependent on the server configuration. When the FTP server is contacted, it asks for a user name and password. Users log in as "anonymous" and can access files on the server. By convention, users input their e-mail address as the password. Typically, users can download files but are unable to upload, change or delete them. If some users must be given those rights, the usual procedure is to set up a separate upload directory to maintain the security of the download section. For example, if your Web site is hosted by an Internet service provider, you might FTP Web site updates to such a directory. The Internet service provider would retrieve the updates from that directory. Without a firewall that provides authentication and privacy via virtual private networks, password-protected FTP is useful only for files of minor importance. Between client and server, FTP passes user names and passwords in clear text, which can easily be stolen. As an application, FTP is typically built into communications software, which supports other common file transfer protocols, such as Xmodem, Ymodem, Zmodem and Kermit. Xmodem, which transmits 128-byte blocks, was the first FTP for PCs. It performs a checksum on packets to help ensure accurate transmission. The sending computer uses an algorithm that calculates the binary values in a packet and sends the result as a tail on the packet. The receiving computer goes through the same algorithm. If the two sums match, then it's fine; if not, it requests that the packet be re-sent. Ymodem, which transmits 1,024-byte blocks, adds batch file processing to Xmodem. Both are stop-and-wait protocols. The sending computer transmits, waits to receive an acknowledgment, or ACK, from the receiving computer that the packet was received intact. A negative acknowledgment, or NAK, indicates a bad or missing packet and requests that the sending computer re-send the packet. Zmodem is a streaming protocol. The sending computer keeps sending packets until it gets a NAK. Then it backs up to the bad packet and resends from there. Zmodem also adjusts packet size, depending on line conditions. If transmission is interrupted midtransfer, Zmodem can restart and resume sending from the point at which it was interrupted. It's often used for satellite transmissions because of its ability to handle changeable line conditions. Kermit was developed in 1981 at Columbia University. When it breaks a file into packets, each packet is bracketed by control data. The receiving computer checks each packet's control data as it arrives and sends an ACK or NAK, as applicable, to the sending computer. The default communications protocol for the Web, Hypertext Transfer Protocol (HTTP), is used to transmit HTML pages from Web server to client browser. HTTP Secure offers a security option that FTP doesn't. And an HTML-coded page allows for greater complexity and flexibility in layout than does straight ASCII text. However, even with caching and persistent connections, HTTP adds overhead to a Web download. Which of the following protocol is used for email services?SMTP stands for Simple mail Transfer Protocol, it is a protocol used for sending e-mail messages between servers.
Which protocol is used to send email messages quizlet?Simple mail transfer protocol (SMTP) is the protocol responsible for sending e-mail messages from an e-mail client to an e-mail server.
Which of the following TCP IP protocol is used for transferring electronic mail messages?SMTP is part of the application layer of the TCP/IP protocol. Using a process called "store and forward," SMTP moves your email on and across networks. It works closely with something called the Mail Transfer Agent (MTA) to send your communication to the right computer and email inbox.
Which of the following protocols is used to send an email message to the first server?The correct answer is SMTP and POP. SMTP stands for Simple Mail Transfer Protocol. The Simple Mail Transfer Protocol (SMTP) is an internet standard communication protocol for electronic mail transmission. Mail servers and other message transfer agents use SMTP to send and receive mail messages.
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