Simple Mail Transfer Protocol (SMTP) - Revision history

Shahroma: /* Security */

2009-12-21T16:09:13Z

Security

← Older revision		Revision as of 16:09, 21 December 2009
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	==Security==		==Security==
	Many critical [[Email_Security\|security]] issues related to emails and emails agents, one of the most used agents is Sendmail, it is complicated and big program that have many functions including mail translation and mail alias names. Sendmail mainly use SMTP which run NVT Telnet , as known Telnet has so many security issues by using open text format to send data, NVT Telnet use port 25, if any body try to break into a computer this is a great security hole to do so, other limitation on original SMTP is it has no way to authenticate senders. some easy solutions are used by using more secure and efficient mail agents written with some kind of mail encryption and spam filter, or even have an assistant virus scanner to scan emails before can be open.<sup>[2,3]</sup>		Many critical [[Email_Security\|security]] issues related to emails and emails agents, one of the most used agents is Sendmail, it is complicated and big program that have many functions including mail translation and mail alias names. Sendmail mainly use SMTP which run NVT Telnet , as known Telnet has so many security issues by using open text format to send data, NVT Telnet use port 25, if any body try to break into a computer this is a great security hole to do so, other limitation on original SMTP is it has no way to authenticate senders. some easy solutions are used by using more secure and efficient mail agents written with some kind of mail encryption and spam filter, or even have an assistant virus scanner to scan emails before can be open.<sup>[2,3]</sup>
-	Call back verification also can be used as validate email address this mostly used as ant spam measure, other solution as modify SMTP intensively not practical as so many installation is depends on how SMTP already build.	+	Call back verification also can be used as validate email address this mostly used as ant spam measure, other solution as modify SMTP intensively not practical as so many installation is depends on how SMTP already build.
-		+

	==Commands Example==		==Commands Example==

Shahroma at 14:49, 12 April 2009

2009-04-12T14:49:06Z

← Older revision		Revision as of 14:49, 12 April 2009
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-	When email is received by your computer, SMTP added time to the mail header this feature also include store tracking data of all hosts that relayed the message. Usually SMTP Message Transfer Agent is used to show the time stamp at the start of message, as well as the sender and each time that an item relayed this time stamp shows the ID for the host send the message, the ID ~~that received~~ the message, and the time that the message was received, the important of this information become from the fact that most of the time stamp and host identity enhance the chance for the receiver to distinguish between email sent from a trusted destination or crackers, also it provide an important information if a problem in mail delivery happened.<sup>[2]</sup>	+	When email is received by your computer, SMTP added time to the mail header this feature also include store tracking data of all hosts that relayed the message. Usually SMTP Message Transfer Agent is used to show the time stamp at the start of message, as well as the sender and each time that an item relayed, this time stamp shows the ID for the host send the message, the ID of the message receiver , and the time that the message was received, the important of this information become from the fact that most of the time stamp and host identity enhance the chance for the receiver to distinguish between email sent from a trusted destination or crackers, also it provide an important information if a problem in mail delivery happened.<sup>[2]</sup>
	Time stamps not always a reliable information source as computer clocks are sometimes inaccurately set , or the information sequence is not make since, adding the time stamp is optional by the recipient user agent.		Time stamps not always a reliable information source as computer clocks are sometimes inaccurately set , or the information sequence is not make since, adding the time stamp is optional by the recipient user agent.

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	==Mail Bouncing==		==Mail Bouncing==
-	It is not always true that every email will be delivered to its destination , this happened if the sender provide incorrect recipient ID, in this case the email send back to ~~originator~~ with a message indicate the reason of why the mail not delivered , the returned email called Bounced email.<sup>[2]</sup>	+	It is not always true that every email will be delivered to its destination , this happened if the sender provide incorrect recipient ID, in this case the email send back to the sender with a message indicate the reason of why the mail not delivered, the returned email called Bounced email.<sup>[2]</sup>

	<br clear=all/>		<br clear=all/>

	==Security==		==Security==
-	Many critical [[Email_Security\|security]] issues related to emails and emails agents, one of the most used agents is Sendmail, it is complicated and big program that have many functions including mail translation and mail alias names. ~~Send mail~~ mainly use SMTP which run NVT ~~telnet~~ , as known ~~telnet~~ has so many security issues by using open text format to send data, NVT ~~telnet~~ use port 25 , if any body try to break into a computer this is a great security hole to do so, other limitation on original SMTP is it has no way to authenticate senders. some easy solutions are used by using more secure and efficient mail agents written with some kind of mail encryption and spam filter, or even have an assistant virus scanner to scan emails before can be open.<sup>[2,3]</sup>	+	Many critical [[Email_Security\|security]] issues related to emails and emails agents, one of the most used agents is Sendmail, it is complicated and big program that have many functions including mail translation and mail alias names. Sendmail mainly use SMTP which run NVT Telnet , as known Telnet has so many security issues by using open text format to send data, NVT Telnet use port 25, if any body try to break into a computer this is a great security hole to do so, other limitation on original SMTP is it has no way to authenticate senders. some easy solutions are used by using more secure and efficient mail agents written with some kind of mail encryption and spam filter, or even have an assistant virus scanner to scan emails before can be open.<sup>[2,3]</sup>
-	~~call~~ back verification also can be used as validate email address this mostly used as ant spam measure, other solution as modify SMTP intensively not practical as so many installation is depends on how SMTP ~~Already~~ build.	+	Call back verification also can be used as validate email address this mostly used as ant spam measure, other solution as modify SMTP intensively not practical as so many installation is depends on how SMTP already build.

Shahroma at 14:42, 12 April 2009

2009-04-12T14:42:48Z

← Older revision		Revision as of 14:42, 12 April 2009
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	This model is used to send email messages over the internet from one machine to another, the message then can be retrieved from the local client with an email agent using POP protocol, configure both protocols required to have the complete picture. Negotiation between Sender and receiver may occur over the several recipients, if the receiver is successfully processed and accepted SMTP will send email data, the receiver send an Okay reply when data received.<sup>[1]</sup>		This model is used to send email messages over the internet from one machine to another, the message then can be retrieved from the local client with an email agent using POP protocol, configure both protocols required to have the complete picture. Negotiation between Sender and receiver may occur over the several recipients, if the receiver is successfully processed and accepted SMTP will send email data, the receiver send an Okay reply when data received.<sup>[1]</sup>

-	[[Image:Component of email system.jpg\|left\|500px\|thumb\|Components of an electronic ~~email~~ system]]	+	[[Image:Component of email system.jpg\|left\|500px\|thumb\|Components of an electronic mail system (SMTP) model]]

Shahroma at 14:40, 12 April 2009

2009-04-12T14:40:43Z

← Older revision		Revision as of 14:40, 12 April 2009
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	==SMTP Model==		==SMTP Model==

-	SMTP Required reliable ordered data stream channel to transfer mail uses the following model of ~~communications~~:	+	SMTP Required reliable ordered data stream channel to transfer mail uses the following model of communication:

	* Mail request start with a command.		* Mail request start with a command.

Shahroma at 21:18, 11 April 2009

2009-04-11T21:18:44Z

← Older revision		Revision as of 21:18, 11 April 2009
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-	SMTP is straight forward, simple, and efficient protocol to transfer mail between machines over the internet. It was first defined in RFC 821. To send mail a sender (client) establish a TCP connection to the receiver (server). SMTP uses a readable simple ASCII text in which one or more recipients ~~of mail~~ are defined.<sup>[3]</sup>	+	SMTP is straight forward, simple, and efficient protocol to transfer mail between machines over the internet. It was first defined in RFC 821. To send mail a sender (client) establish a TCP connection to the receiver (server). SMTP uses a readable simple ASCII text in which one or more recipients are defined.<sup>[3]</sup>

	==SMTP Model==		==SMTP Model==

Shahroma at 21:18, 11 April 2009

2009-04-11T21:18:17Z

← Older revision		Revision as of 21:18, 11 April 2009
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-	==~~SMTP~~ Commands Example==	+	==Commands Example==
	Every SMTP transmission consist of a sequence of commands and responses between the server and the client, these commands format is easy to understand because each command appears on a separate line. Here is some of commands and their meanings. <sup>[3]</sup>		Every SMTP transmission consist of a sequence of commands and responses between the server and the client, these commands format is easy to understand because each command appears on a separate line. Here is some of commands and their meanings. <sup>[3]</sup>

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	<br clear=all/>		<br clear=all/>

-	== Reply Codes==	+	== Reply Codes Example==
	SMTP reply code look like FTP reply code in structure, it consist of three digits the first digit show the status of the command.<sup>[3]</sup>		SMTP reply code look like FTP reply code in structure, it consist of three digits the first digit show the status of the command.<sup>[3]</sup>

Shahroma at 20:34, 11 April 2009

2009-04-11T20:34:07Z

← Older revision		Revision as of 20:34, 11 April 2009
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	<br clear=all/>		<br clear=all/>

-	===Mail Bouncing===	+	==Mail Bouncing==
	It is not always true that every email will be delivered to its destination , this happened if the sender provide incorrect recipient ID, in this case the email send back to originator with a message indicate the reason of why the mail not delivered , the returned email called Bounced email.<sup>[2]</sup>		It is not always true that every email will be delivered to its destination , this happened if the sender provide incorrect recipient ID, in this case the email send back to originator with a message indicate the reason of why the mail not delivered , the returned email called Bounced email.<sup>[2]</sup>

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	<br clear=all/>		<br clear=all/>

-	=== Reply Codes===	+	== Reply Codes==
	SMTP reply code look like FTP reply code in structure, it consist of three digits the first digit show the status of the command.<sup>[3]</sup>		SMTP reply code look like FTP reply code in structure, it consist of three digits the first digit show the status of the command.<sup>[3]</sup>

Shahroma at 20:31, 11 April 2009

2009-04-11T20:31:37Z

← Older revision		Revision as of 20:31, 11 April 2009
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	HELO : Identify the sender		HELO : Identify the sender
-	MAIL ~~FORM~~ : Start mail transaction and identify mail originator	+	MAIL FROM : Start mail transaction and identify mail originator
	RCOT TO : Identify an individual recipient		RCOT TO : Identify an individual recipient
	DATA : Sender is ready to transmit a series of line of text		DATA : Sender is ready to transmit a series of line of text
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	TURN : Ask partiner to switch roles and become a sender		TURN : Ask partiner to switch roles and become a sender
	SOML : Send email if receiver is logged in, deliver direct to the terminal		SOML : Send email if receiver is logged in, deliver direct to the terminal
		+	SEND : Deliver the mail directly to the recipient if logged in
		+	QUIT : Close connection

		+
		+	<br clear=all/>
		+
		+	=== Reply Codes===
		+	SMTP reply code look like FTP reply code in structure, it consist of three digits the first digit show the status of the command.<sup>[3]</sup>
		+
		+	1yz : Positive primary reply
		+	2yz : Positive completion reply
		+	3yz : Positive intermediate reply
		+	4yz : Try again reply
		+	5yz : Permanent negative reply
		+	x0z : Syntax error or unknown command
		+	x1z : Information request
		+	x2z : Connection reference reply
		+	x5z : Status of the receiver mail system
		+
		+	x4z, and x5z : Unspecified as yet.
		+
	<br clear=all/>		<br clear=all/>

Shahroma at 20:18, 11 April 2009

2009-04-11T20:18:22Z

← Older revision		Revision as of 20:18, 11 April 2009
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	*[http://en.wikipedia.org/wiki/SMTP_proxy SMTP Proxy ]		*[http://en.wikipedia.org/wiki/SMTP_proxy SMTP Proxy ]
	*[http://en.wikipedia.org/wiki/Anti-Spam_SMTP_Proxy Anti spam SMTP proxy]		*[http://en.wikipedia.org/wiki/Anti-Spam_SMTP_Proxy Anti spam SMTP proxy]
-		+	*[http://www.sendmail.org/ Sendmail.org]
		+
	--[[User:Shahroma\|Shahroma]] 20:51, 2 April 2009 (EDT) Mohammad Shahrouri		--[[User:Shahroma\|Shahroma]] 20:51, 2 April 2009 (EDT) Mohammad Shahrouri

Shahroma at 20:13, 11 April 2009

2009-04-11T20:13:03Z

← Older revision		Revision as of 20:13, 11 April 2009
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-	SMTP is straight forward, simple, efficient protocol to transfer mail between machines, It was first defined in RFC 821. ~~SMTP has two rules regarding the hosts,~~a sender ~~acts as~~ client it establish a TCP connection ~~with~~ the receiver ~~, which act like a~~ server. SMTP uses a readable simple ~~text-based~~ ASCII text in which one or more recipients of mail are defined.<sup>[3]</sup>	+	SMTP is straight forward, simple, and efficient protocol to transfer mail between machines over the internet. It was first defined in RFC 821. To send mail a sender (client) establish a TCP connection to the receiver (server). SMTP uses a readable simple ASCII text in which one or more recipients of mail are defined.<sup>[3]</sup>

	==SMTP Model==		==SMTP Model==