Introductio
Electronicmail(electronicmail)referstoacomputercommunicationnetwork-basedinformationdeliveryservicethatusesstore-and-forwardmethodtoprovideuserswithletterexchange.Theusersendstheinformationtobesentintothecommunicationnetworkinaprescribedformat,processedandtransmitted,andfinallysenttothereceivinguser'se-mailboxsetonthecomputer,andtherecipientisnotified.Receivinguserscanopentheirmailboxestoreadlettersanytime,anywhere.
IPMbusinessfunctionmodel
Aninterpersonalletter(IPM)businessfunctionmodelfortransmittingordinarylettersisshowninFigure1.ThecommunicationbetweenIPMusersisrealizedthroughtheIPMuseragent(IPM-UA)andmessagestorage(MS)receivingthemessagetransfer(MT)service.Itcancommunicatewiththetelegraphservicethroughthepublicusertelegraphaccessunit(PTLXAU);communicatewiththesmarttelegraph(TTX)servicethroughthesmartusertelegraphaccessunit(TLMA),andallowthesmartusertelegramusertojointheIPMserviceasanIPMuser;Throughtheinterfacewiththepostalsystem(PDAU),itisconvertedintoordinarylettersanddeliveredbythepostofficetorecipientsoutsidethemessageprocessingsystem(MHS).PDAUcanbeseenascomposedofmultipleuseragents(UA),andeachUAisidentifiedbyapostofficeaddress.
Compositio
Aletteriscomposedofanenvelopeandcontent.Thecontentoftheletterisdividedintotwoparts:theheaderandthebody.Theheadercontainsattributesrelatedtothecharacteristicsoftheletter.Thebodyistheinformationthatthesenderwantsthereceivertoobtain,usuallycomposedofoneormoresegments.Eachsegmentcanhavedifferenttypesofcodedinformation.Letterenvelopescanbedividedintothreeforms:deliveryenvelope,deliveryenvelopeandrelayenvelope.ThesendinguserinteractswiththeUAandpreparesthebodyoftheletter.TheUAaddsaletterheadertoitbasedontheuser'sinputtoindicatethesender,receiver,sendingtime,andlettertitleoftheletter,andthenprescribethedeliveryenvelope.Thedeliveryenvelopeindicatestherelevantcontrolinformationduringthedeliveryprocess,suchaswhichmessagetransferagent(MTA)todeliverto.TheMTAanalyzesandmodifiessomecontrolinformationonthedeliveryenvelopetoturnitintoarelayenvelope,andselectsthenextMTAaccordingtotheaddressontherelayenvelope,uptotheMTAconnectedtothereceivingUA,whichformsthedeliveryenvelope.Finally,thereceivingUAremovestheenvelopeandstoresthecontentoftheletterintherecipient'se-mailboxforretrievalandcopyingbytherecipient.
Officium
Lettereding:usedtocreate and modifyletters.
Mailsending:Thereareurgentletters,privatelettersandregisteredletters.
Receivingandprocessingofletters:youcanreadthecontentoftheletter,youcanalsoreplyorforwardtoothers.
Thestorageandfilingofletters:someimportantletterscanbestored,orafoldercanbecreatedforfuturereference.
Directinvestmentservice:Mailboxuserscandirectlysendletterstofaxmachines,telexmachines,packetterminals,etc.
Filetransmission:Userscantransmitvarioustypesthroughtheelectronicmailsystemdocument.
Multi-languageenvironment:ThesystemalsoprovidescustomerswithChineseandEnglishlanguageenvironments,andcustomerscanchoosetouseChineseorEnglishaccordingtotheirneeds.
Safetyandconfidentiality:Eachmailboxcustomermustenterhismailboxnameandpasswordtoenterhismailbox.Thecustomercanalsohaveaprivatepassword.Forprivateletters,thecustomermustenterthemailboxnameandpassword.Thislettercanonlybereadbyenteringtheprivatepassword.Thismethodcanalsobeusedtoshareamailboxamongmultiplepeople.
Features
E-mailserviceprovidescustomerswithafriendlycustomerinterface,easytooperate,anduserscanexchangeinformationwithoutleavinghome.
Electronicmailboxovercomestheshortcomingsoftraditionalbusinessintermsoftechnology,economyandusage.Itachievesmultiplefunctionsinonemachineandhasamailbox.Inadditiontocommunicatingwithmailboxusers,itcanalsobegiventoanyoneintheworld.Faxmachineortelexmachinetransmitsinformation.Thee-mailsystemissafeandreliable.Ithastwopasswordsthatusershavetherighttomodifyatanytime.Theprivatepasswordisusedtoreadconfidentialprivateletters.Whenthepassword(orusername)isenteredincorrectlythreetimesinarow,thesystemwillrecordit.
Thee-mailserviceistheunificationofreal-timecommunicationandnon-real-timecommunication.Itcanreceiveletterswhentheusershutsdown(non-real-time);itcanalsosenddesignatedletterstodesignatedfaxmachinesortelephonesinrealtime.Onthemachine(real-time),soastoachievetheunityofthetwo.Themailboxbusinessisnotrestrictedbytimeandspace.Customerscanopenthemailboxatanytimeandplacetosendandreceiveletters.ButnowtheInternetvirusisflooding,especiallythroughe-mail,soyoushouldchooseagoodvirusprotection.