10. Electronic Mail

10.1 Electronic mailAdvantagesIt is normally much cheaper than using the telephone (although, as time equates to money for most companies, this relates any savings or costs to a user’s typing speed).Many different types of data can be transmitted, such as images, documents, speech, and so on.It is much faster than the postal service.Users can filter incoming email easier than incoming telephone calls.It normally cuts out the need for work to be typed, edited and printed by a secretary.It reduces the burden on the mailroom.It is normally more secure than traditional methods.It is relatively easy to send to groups of people (traditionally, either a circulation list was required or a copy to everyone in the group was required).It is usually possible to determine whether the recipient has actually read the message (the electronic mail system sends back an acknowledgement).

AdvantagesIt is normally much cheaper than using the telephone (although, as time equates to money for most companies, this relates any savings or costs to a user’s typing speed).Many different types of data can be transmitted, such as images, documents, speech, and so on.It is much faster than the postal service.Users can filter incoming email easier than incoming telephone calls.It normally cuts out the need for work to be typed, edited and printed by a secretary.It reduces the burden on the mailroom.It is normally more secure than traditional methods.It is relatively easy to send to groups of people (traditionally, either a circulation list was required or a copy to everyone in the group was required).It is usually possible to determine whether the recipient has actually read the message (the electronic mail system sends back an acknowledgement).

DisadvantagesIt stops people using the telephone.It cannot be used as a legal document.Electronic mail messages can be sent impulsively and may be later regretted (sending by traditional methods normally allows for a rethink). In extreme cases messages can be sent to the wrong person (typically when replying to an email message, where a message is sent to the mailing list rather than the originator).It may be difficult to send to some remote sites. Many organisations have either no electronic mail or merely an intranet. Large companies are particularly wary of Internet connections and limit the amount of external traffic.Not everyone reads their electronic mail on a regular basis (although this is changing as more organisations adopt email as the standard communications medium).

DisadvantagesIt stops people using the telephone.It cannot be used as a legal document.Electronic mail messages can be sent impulsively and may be later regretted (sending by traditional methods normally allows for a rethink). In extreme cases messages can be sent to the wrong person (typically when replying to an email message, where a message is sent to the mailing list rather than the originator).It may be difficult to send to some remote sites. Many organisations have either no electronic mail or merely an intranet. Large companies are particularly wary of Internet connections and limit the amount of external traffic.Not everyone reads their electronic mail on a regular basis (although this is changing as more organisations adopt email as the standard communications medium).StandardsSimple Mail Transfer Protocol (SMTP) – which is used with the TCP/IP protocol suite. It has traditionally been limited to the text-based electronic messages.Multipurpose Internet Mail Extension (MIME) – which allows the transmission and reception of mail that contains various types of data, such as speech, images and motion video. It is a newer standard than SMTP and uses much of its basic protocol.S/MIME (Secure MIME). RSA Data Security created S/MIME which supports encrypted email

transfers and digitally signed electronic mail.

StandardsSimple Mail Transfer Protocol (SMTP) – which is used with the TCP/IP protocol suite. It has traditionally been limited to the text-based electronic messages.Multipurpose Internet Mail Extension (MIME) – which allows the transmission and reception of mail that contains various types of data, such as speech, images and motion video. It is a newer standard than SMTP and uses much of its basic protocol.S/MIME (Secure MIME). RSA Data Security created S/MIME which supports encrypted email

transfers and digitally signed electronic mail.

10.2 Email client/server or message transfer agent

Post offices – where outgoing messages are temporally buffered (stored) before transmission and where incoming messages are stored. The post office runs the server software capable of routing messages (a message transfer agent) and maintaining the post office database.Message transfer agents – for forwarding messages between post offices and to the destination clients. This software can either reside on the local post office or on a physically separate server.Gateways – which provide part of the message transfer agent functionality. They translate between different email systems, different email addressing schemes and messaging protocols.Email clients – normally the computer which connects to the post office. It contains three parts:

Email API (Application Program Interface): MAPI, VIM, MHS and CMC.Messaging protocol: SMTP/ X.400.Network transport protocol. Ethernet/ FDDI/etc.

Post offices – where outgoing messages are temporally buffered (stored) before transmission and where incoming messages are stored. The post office runs the server software capable of routing messages (a message transfer agent) and maintaining the post office database.Message transfer agents – for forwarding messages between post offices and to the destination clients. This software can either reside on the local post office or on a physically separate server.Gateways – which provide part of the message transfer agent functionality. They translate between different email systems, different email addressing schemes and messaging protocols.Email clients – normally the computer which connects to the post office. It contains three parts:

Email API (Application Program Interface): MAPI, VIM, MHS and CMC.Messaging protocol: SMTP/ X.400.Network transport protocol. Ethernet/ FDDI/etc.

MAPI (messaging API) – Microsoft part of Windows Operation Services Architecture.VIM (vendor-independent messaging) – Lotus, Apple, Novell and Borland derived email API.MHS (message handling service) – Novell network interface which is often used as an email gateway protocol.CMC (common mail call) – Email API associated with the X.400 native messaging protocol.

MAPI (messaging API) – Microsoft part of Windows Operation Services Architecture.VIM (vendor-independent messaging) – Lotus, Apple, Novell and Borland derived email API.MHS (message handling service) – Novell network interface which is often used as an email gateway protocol.CMC (common mail call) – Email API associated with the X.400 native messaging protocol.

Localpost office

Messagetransferagent

Remotepost office

Localpost office

Remotepost office

Real-timeremotetransfer



Message transfer agentforwards mail to the remote(store and forward)

Mail messageis forwarded tolocal post office

Message transfer byreal-time transfers

10.3 Email architecture

Email server– Server post office software– Email database– Email message transfer agent– Email routing information– Directory synchronization

Email server– Gateway software

External connection

Email client– Email client software

Gateway protocols:MHS (used with Novell NetWare).SMTP.MIME (used with Internet environment).X.400 (used with X.400).MS Mail (used with Microsoft Mail).cc:Mail (used with Lotus cc:Mail).

Gateway protocols:MHS (used with Novell NetWare).SMTP.MIME (used with Internet environment).X.400 (used with X.400).MS Mail (used with Microsoft Mail).cc:Mail (used with Lotus cc:Mail).

10.4 SMTP (RFC 821)

Sender Receiver

HELO domain

250 OK

250 OK

250 OK

354

MAIL FROM: sender

RCPT TO: receiver

DATA

message

LF CR

LF CR

250 OK

SMTP commands:HELO domainMAIL FROM: sender-addressRCPT FROM: receiver-addressDATARSEYQUITEXPN mailing-listSEND FROM: sender-addressSOML FROM: sender-addressVRFY username

SMTP commands:HELO domainMAIL FROM: sender-addressRCPT FROM: receiver-addressDATARSEYQUITEXPN mailing-listSEND FROM: sender-addressSOML FROM: sender-addressVRFY username

SMTP responses:211 System status214 Help message220 Service ready221 Service closing transmission

channel250 Request mail action

completed successfully251 Addressed user does not

exist on system but will forward receiver-address

354 Indicate to the sender that the mail message can now be sent. The end of the message is identified by two CR, LF characters

421 Service is not available450 Mailbox unavailable and the

requested mail action was not taken

SMTP responses:211 System status214 Help message220 Service ready221 Service closing transmission

channel250 Request mail action

completed successfully251 Addressed user does not

exist on system but will forward receiver-address

354 Indicate to the sender that the mail message can now be sent. The end of the message is identified by two CR, LF characters

421 Service is not available450 Mailbox unavailable and the

requested mail action was not taken

10.5 Example (RFC821)

> mail -v [email protected]: TestThis is a test message. Hello, how are you.Fred.

EOT

[email protected]... Connecting to central.napier.ac.uk. (smtp)...220 central.napier.ac.uk ESMTP Sendmail 8.9.1/8.9.1; Fri, 18 Dec 1998 15:55:45 GMT>>> HELO www.eece.napier.ac.uk250 central.napier.ac.uk Hello [email protected] [146.176.151.139], pleased to

meet you>>> MAIL From:<[email protected]>250 <[email protected]>... Sender ok>>> RCPT To:<[email protected]>250 <[email protected]>... Recipient ok>>> DATA354 Enter mail, end with "." on a line by itself>>> .250 PAA24767 Message accepted for [email protected]... Sent (PAA24767 Message accepted for delivery)Closing connection to central.napier.ac.uk.>>> QUIT221 central.napier.ac.uk closing connection

> mail -v [email protected]: TestThis is a test message. Hello, how are you.Fred.

EOT

[email protected]... Connecting to central.napier.ac.uk. (smtp)...220 central.napier.ac.uk ESMTP Sendmail 8.9.1/8.9.1; Fri, 18 Dec 1998 15:55:45 GMT>>> HELO www.eece.napier.ac.uk250 central.napier.ac.uk Hello [email protected] [146.176.151.139], pleased to

meet you>>> MAIL From:<[email protected]>250 <[email protected]>... Sender ok>>> RCPT To:<[email protected]>250 <[email protected]>... Recipient ok>>> DATA354 Enter mail, end with "." on a line by itself>>> .250 PAA24767 Message accepted for [email protected]... Sent (PAA24767 Message accepted for delivery)Closing connection to central.napier.ac.uk.>>> QUIT221 central.napier.ac.uk closing connection

10.6 RFC822

From [email protected] Wed Jul 5 12:36:49 1995Received: from ACOMP.CO.UK ([154.220.12.27]) by central.napier.ac.uk (8.6.10/8.6.10) with SMTP id MAA16064 for <[email protected]>;

Wed, 5 Jul 1995 12:36:43 +0100

Received: from WPOAWUK-Message_Server by ACOMP.CO.UK with Novell_GroupWise; Wed, 05 Jul 1995 12:35:51 +0000

Message-Id: <[email protected] >

X-Mailer: Novell GroupWise 4.1

Date: Wed, 05 Jul 1995 12:35:07 +0000

From: Fred Bloggs <[email protected]>

To: [email protected]: Technical QuestionStatus: REO

Dear BillI have a big problem. Please help.

Fred

From [email protected] Wed Jul 5 12:36:49 1995Received: from ACOMP.CO.UK ([154.220.12.27]) by central.napier.ac.uk (8.6.10/8.6.10) with SMTP id MAA16064 for <[email protected]>;

Wed, 5 Jul 1995 12:36:43 +0100

Received: from WPOAWUK-Message_Server by ACOMP.CO.UK with Novell_GroupWise; Wed, 05 Jul 1995 12:35:51 +0000

Message-Id: <[email protected] >

X-Mailer: Novell GroupWise 4.1

Date: Wed, 05 Jul 1995 12:35:07 +0000

From: Fred Bloggs <[email protected]>

To: [email protected]: Technical QuestionStatus: REO

Dear BillI have a big problem. Please help.

Fred RFC822 defines:A header – which is basically the mail header and contains information for the successful transmission and delivery of a message. This typically contains the email addresses for sender and receiver, the time the message was sent and received. Any computer involved in the transmission can added to the header.The contents.

RFC822 defines:A header – which is basically the mail header and contains information for the successful transmission and delivery of a message. This typically contains the email addresses for sender and receiver, the time the message was sent and received. Any computer involved in the transmission can added to the header.The contents.

MessageMessage

MessageMessage

RFC822header

RFC822header

MessageMessage

Singletext filesent

10.7 Example email message showing RFC822 part

10.8 MIME (Multipurpose Internet Mail Extension )SMTP drawbacks:SMTP can only transmit ASCII characters and thus cannot transmit executable files or other binary objects.SMTP does not allow the attachment of files, such as images and audio.SMTP can only transmit 7-bit ASCII character thus it does support an extended ASCII character set.

SMTP drawbacks:SMTP can only transmit ASCII characters and thus cannot transmit executable files or other binary objects.SMTP does not allow the attachment of files, such as images and audio.SMTP can only transmit 7-bit ASCII character thus it does support an extended ASCII character set.

RFC1521/RFC1522 (MIME)Five new message header fields in the RFC 822 header, which provide extra information about the body of the message.Use of various content formats to support multimedia electronic mail.Defined transfer encodings for transforming attached files.

RFC1521/RFC1522 (MIME)Five new message header fields in the RFC 822 header, which provide extra information about the body of the message.Use of various content formats to support multimedia electronic mail.Defined transfer encodings for transforming attached files.

New headersMIME-version – a message that conforms to RFC 1521 or 1522 is MIME-version 1.0.Content-type – this field defines the type of data attached. Content-transfer-encoding – this field indicates the type of transformation necessary to represent the body in a format which can be transmitted as a message.Content-id – this field is used to uniquely identify MIME multiple attachments in the email message.Content-description – this field is a plain-text description of the object with the body. It can be used by the user to determine the data type.

New headersMIME-version – a message that conforms to RFC 1521 or 1522 is MIME-version 1.0.Content-type – this field defines the type of data attached. Content-transfer-encoding – this field indicates the type of transformation necessary to represent the body in a format which can be transmitted as a message.Content-id – this field is used to uniquely identify MIME multiple attachments in the email message.Content-description – this field is a plain-text description of the object with the body. It can be used by the user to determine the data type.

MIME-Version: 1.0Content-Type: text/plain; charset=us-asciiContent-Transfer-Encoding: 7bit

MIME-Version: 1.0Content-Type: text/plain; charset=us-asciiContent-Transfer-Encoding: 7bit

Received: from pc419.eece.napier.ac.uk by ccmailgate.napier.ac.uk (SMTPLINK V2.11.01) ; Fri, 24 Jan 97 11:13:41 gmtReturn-Path: <[email protected]>Message-ID: <[email protected]>Date: Fri, 24 Jan 1997 11:14:22 -0800From: Dr William Buchanan <[email protected]>Organization: Napier UniversityX-Mailer: Mozilla 3.01 (Win95; I; 16bit)MIME-Version: 1.0To: [email protected]: Book recommendationContent-Type: text/plain; charset=us-asciiContent-Transfer-Encoding: 7bit

Received: from pc419.eece.napier.ac.uk by ccmailgate.napier.ac.uk (SMTPLINK V2.11.01) ; Fri, 24 Jan 97 11:13:41 gmtReturn-Path: <[email protected]>Message-ID: <[email protected]>Date: Fri, 24 Jan 1997 11:14:22 -0800From: Dr William Buchanan <[email protected]>Organization: Napier UniversityX-Mailer: Mozilla 3.01 (Win95; I; 16bit)MIME-Version: 1.0To: [email protected]: Book recommendationContent-Type: text/plain; charset=us-asciiContent-Transfer-Encoding: 7bit

10.9 MIME content (mixed)

MIME content headerstext/plaintext/richtextmultipart/mixedmultipart/parallelmultipart/alternativemultipart/digestmessage/rfc822message/partialmessage/external-bodyimage/jpegimage/gifvideo/mpegaudio/basicapplication/postscriptapplication/octet-stream


MIME content headersFrom: Dr William Buchanan <[email protected]>MIME-Version: 1.0To: [email protected]: Any subjectContent-Type: multipart/mixed; boundary=“boundary name”This part of the message will be ignored.-- boundary nameContent-Type: multipart/mixed; boundary=“boundary name”This is the first mail message part.-- boundary nameAnd this is the second mail message part.-- boundary name --

MIME content headersFrom: Dr William Buchanan <[email protected]>MIME-Version: 1.0To: [email protected]: Any subjectContent-Type: multipart/mixed; boundary=“boundary name”This part of the message will be ignored.-- boundary nameContent-Type: multipart/mixed; boundary=“boundary name”This is the first mail message part.-- boundary nameAnd this is the second mail message part.-- boundary name --

Example MIME file with 3 fragments (first part)From: Fred Bloggs <[email protected]>MIME-Version: 1.0To: [email protected]: Any subjectContent-Type: message/partial;

id=“[email protected]”; number=1; total=3Content=type: video/mpeg

First part of MPEG file

Example MIME file with 3 fragments (second part)From: Fred Bloggs <[email protected]>MIME-Version: 1.0To: [email protected]: Any subjectContent-Type: message/partial;


Second part of MPEG file

Example MIME file with 3 fragments (third part)From: Fred Bloggs <[email protected]>MIME-Version: 1.0To: [email protected]: Any subjectContent-Type: message/partial;

id=“[email protected]”; number=3; total=3Content=type: video/mpegThird part of MPEG file

Example MIME file with 3 fragments (first part)From: Fred Bloggs <[email protected]>MIME-Version: 1.0To: [email protected]: Any subjectContent-Type: message/partial;


First part of MPEG file

Example MIME file with 3 fragments (second part)From: Fred Bloggs <[email protected]>MIME-Version: 1.0To: [email protected]: Any subjectContent-Type: message/partial;


Second part of MPEG file

Example MIME file with 3 fragments (third part)From: Fred Bloggs <[email protected]>MIME-Version: 1.0To: [email protected]: Any subjectContent-Type: message/partial;

id=“[email protected]”; number=3; total=3Content=type: video/mpegThird part of MPEG file

10.10MIME content (partial)



10.11MIME encodings7bit – no encoding, and all of the characters are 7-bit ASCII characters.8bit – no encoding, and extended 8-bit ASCII characters are used.quoted-printable – encodes the data so that non-printing ASCII characters (such as line feeds and carriage returns) are displayed in a readable form.base64 – encodes by mapping 6-bit blocks of input to 8-bit blocks of output, all of which are printable ASCII characters.x-token – another non-standard encoding method.

E.g. Content-transfer-encoding: quoted-printable

7bit – no encoding, and all of the characters are 7-bit ASCII characters.8bit – no encoding, and extended 8-bit ASCII characters are used.quoted-printable – encodes the data so that non-printing ASCII characters (such as line feeds and carriage returns) are displayed in a readable form.base64 – encodes by mapping 6-bit blocks of input to 8-bit blocks of output, all of which are printable ASCII characters.x-token – another non-standard encoding method.

E.g. Content-transfer-encoding: quoted-printable

Quotable-printable:Message has been encoded so that all non-printing characters have been converted to printable characters. A typical transform is to insert =xx where xx is the hexadecimal equivalent for the ASCII character. A form feed (FF) would be encoded with ‘=0C’

Quotable-printable:Message has been encoded so that all non-printing characters have been converted to printable characters. A typical transform is to insert =xx where xx is the hexadecimal equivalent for the ASCII character. A form feed (FF) would be encoded with ‘=0C’

Bit value Encoded character




0 A 16 Q 32 g 48 w 1 B 17 R 33 h 49 x 2 C 18 S 34 i 50 y 3 D 19 T 35 j 51 z 4 E 20 U 36 k 52 0 5 F 21 V 37 l 53 1 6 G 22 W 38 m 54 2 7 H 23 X 39 n 55 3 8 I 24 Y 40 o 56 4 9 J 25 Z 41 p 57 5 10 K 26 a 42 q 58 6 11 L 27 b 43 r 59 7 12 M 28 c 44 s 60 8 13 N 29 d 45 t 61 9 14 O 30 e 46 u 62 + 15 P 31 f 47 v 63 /

10.12 Just for funSmilie Description Smilie Description :-) smile :-> sarcastic ;-) wink :-))) laughing or double chin :.-) laughing tears ;-)=) grin :-D laughing :-} wry smile :-P tongue :-( sad, angry :-< sad :-I indifferent/sad :.-( weeping :-II angry :-@ angry }-) evil :-X mute :-() talking :-O surprised/shocked =:-) shocked O:-) halo :-3 has eaten a lemon :-/ sceptical :-Z sleeping :-x kissing :-* sorry, I didn't want to say that ?-( sorry, I don't know what went

wrong :*) drunk (red nose)

%-) stared too long at monitor #-) dead X-) unconscious :-Q smoking (:-) bald .-) one-eyed -:-) punk <:-) stupid question (donkey’s hat) <|-) chinese @:-) arab 8:-) little girl :-)-8 big girl [:-] robot ::-) wearing glasses 8-) wearing glasses / wide-eyed grin B-) horn-rimmed glasses B:-) sunglasses on head .^) side view :<) moustache _O-) aquanaut {:-) wig :-E vampire :-[ vampire (-: left-handed :o) boxer's nose :) happy [:] robot :] gleep, friendly =) variations on a theme :} (what should we call these?) :> (what?) :@ (what?) :D laughter :I hmmm... :( sad

10.13 JFF Part IIAcro-nym

Description Acronym Description

2U2 to you, too AAMOF as a matter of fact AFAIK as far as I know AFK away from keyboard ASAP as soon as possible BBL be back later BOT back on topic BRB be right back BTW by the way BYORL bring your own rocket launcher C4N ciao for now CFD call for discussion CFV call for vote CU see you CUL see you later CYA see ya DIY do it yourself EOD end of discussion EOT end of transmission F2F face to face FAI frequently argued issue FAQ frequently asked questions FOAF friend of a friend FWIW for what it's worth FYI for your information GAL get a life GFC going for coffee GRMBL grumble GTG got to go HAND have a nice day HTH hope this helps IAC in any case IC I see IDGI I don’t get it IMHO in my humble opinion IMNSHO in my not so humble opinion IMO in my opinion IMPE in my previous/personal

experience IMVHO in my very humble

opinion IOW in other words

IRL in real life KISS keep it simple stupid LOL laughing out loud NC no comment ONNA oh no, not again! OOTC obligatory on-topic content OTOH on the other hand REHI hello again (re-Hi!) ROFL rolling on the floor laughing RTDox read the documentation SHTSI somebody had to say it SO significant other THX thanks TIA thanks in advance TLA three letter acronym TOS terms of service TTFN ta-ta for now TTYL talk to you later WIIWD what it is we do WWDWIIWD when we do what it is we do YGWYPF you get is what you pay for

10. Electronic Mail

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