% references\references\ref{DCome83}\by D.~Comer.\paper The Computer Science Research Network CSnet:A History and Status Report\journal Communications of the ACM\volume 26\issue 10\month October\year 1983\pages 747--753\endref\ref{DCroc79}\by D.H.~Crocker, E.S.~Szurkowski, D.J.~Farber.\paper An Internetwork Memo Distribution Facility~---~MMDF\inbook Proceedings,Sixth Data Communications Symposium\publaddr Asilomar\month November\year 1979\pages 18--25\endref\ref{DCroc82}\by D.H.~Crocker.\paper Standard for the Format of ARPA Internet Text Messages\paperinfo Request for Comments 822\other\publ ARPA Internet Network Information Center (NIC)\publaddr SRI International\month August\year 1982\endref\ref{DEA}\book Data Encryption Algorithm\bookinfo X3.92--1981\publ American National Standards Institute\year 1981\endref\ref{DKing84}\by D.P.~Kingston,~III.\paper MMDFII: A Technical Review\inbook ProceedingsUsenix Summer '84 Conference\publaddr Salt Lake City, Utah\month June\year 1984\pages 32--41\endref\ref{EAllm83}\by E.~Allman.\paper SENDMAIL~---~An Internetwork Mail Router\other\publ Britton-Lee, Inc.\publaddr Berkeley, California\month July\year 1983\endref\ref{EOlse84}\by E.W.~Olsen.\paper NetOS Concepts and Facilities\other\publ Local Network Systems, Inc.\publaddr Costa Mesa, California\month August\year 1984\endref\ref{EStef84}\by E.A.~Stefferud, J.N.~Sweet, T.P.~Domae.\paper MZnet: Mail Service for Personal Micro-Computer Systems\inbook Proceedings,Second International Symposium on Computer Message Systems\publaddr Nottingham, U.K\month May\year 1984\pages 293--302\endref\ref{FIKM}\book Financial Institution Key Management\bookinfo X9.17--198\_ (draft)\publ American National Standards Institute\year 198\_\endref\ref{FIPS46}\book Data Encryption Standard\bookinfo Federal Information Processing Standards,Publication 46\month January\year 1977\endref\ref{FIPS81}\book DES Modes of Operation\bookinfo Federal Information Processing Standards,Publication 81\month December\year 1980\endref\ref{FIPS98}\paper Specification for Message Format for Computer Based Message Systems\other\publ National Bureau of Standards\month January\year 1983\endref\ref{HERMES}\by Bolt, Beranek, and Newman.\paper Hermes User's Manual\paperinfo for TOPS-20\other\publ Bolt, Beranek, and Newman\publaddr Boston, MA\month January\year 1979\endref\ref{IP}\paper Internet Protocol\paperinfo Request for Comments 791 (\milstd/ 1777)\inbook Internet Protocol Transition Workbook\publ ARPA Internet Network Information Center (NIC)\publaddr SRI International\month September\year 1981\endref\ref{JReyn84}\by J.K.~Reynolds.\paper Post Office Protocol\paperinfo Request for Comments 918\other\publ ARPA Internet Network Information Center (NIC)\publaddr SRI International\month October\year 1984\endref\ref{LLamp82}\by L.~Lamport, R.~Shostak, M.~Pease.\paper The Byzantine Generals Problem\journal ACM Transactions on Programming Languages and Systems\volume 4\month July\year 1982\pages 382--401\endref\ref{MButl85}\by M.~Butler, J.B.~Postel, et.~al.\paper Post Office Protocol - Version~2\paperinfo Request for Comments 937\other\publ ARPA Internet Network Information Center (NIC)\publaddr SRI International\month February\year 1985\endref\ref{MRose84a}\by M.T.~Rose.\paper The Rand MH Message Handling System: The UCI BBoards Facility\other\publ Department of Computer and Information Sciences\publaddr University of Delaware\month October\year 1984\endref\ref{MRose84b}\by M.T.~Rose.\paper The Rand MH Message Handling System: Tutorial\other\publ Department of Computer and Information Sciences\publaddr University of Delaware\month October\year 1984\endref\ref{MRose85a}\by M.T.~Rose, J.L.~Romine.\paper The Rand \MH/ Message Handling System: User's Manual\paperinfo UCI Version\other\publ Department of Information and Computer Science\publaddr University of California, Irvine\month January\year 1985\endref\ref{MRose85b}\by M.T.~Rose, E.A.~Stefferud.\paper Proposed Standard for Message Encapsulation\paperinfo Request for Comments 934\other\publ ARPA Internet Network Information Center (NIC)\publaddr SRI International\month January\year 1985\endref\ref{MRose85c}\by M.T.~Rose, D.J.~Farber, S.T.~Walker.\paper Design of the TTI Prototype Trusted Mail Agent\inbook Proceedings,Second International Symposium on Computer Message Systems\publaddr Washington, D.C.\month September\year 1985\toappear\endref\ref{MRose85d}\by M.T.~Rose, E.A.~Stefferud, J.N.~Sweet.\paper MH: A Multifarious User Agent\journal Computer Networks%\volume V\issue N\toappear\endref\ref{SMTP}\paper Simple Mail Transfer Protocol\paperinfo Request for Comments 821\other\publ ARPA Internet Network Information Center (NIC)\publaddr SRI International\month August\year 1982\endref\ref{TCP}\paper Transmission Control Protocol\paperinfo Request for Comments 793 (\milstd/ 1778)\inbook Internet Protocol Transition Workbook\publ ARPA Internet Network Information Center (NIC)\publaddr SRI International\month September\year 1981\endref\ref{VVoyd83}\by V.L.~Voydock, S.T.~Kent.\paper Security Mechanisms in High-Level Network Protocols\journal Computing Surveys\volume 15\issue 2\month June\year 1983\pages 135--171\endref\ref{WJoy83}\by W.N.~Joy, E.~Cooper, R.S.~Fabry, S.J.~Leffler, K.~McKusick, D.~Mosher.\paper 4.2\bsd/ System Manual\paperinfo Technical Report Number 5\publ Computer Systems Research Group, University of California, Berkeley\month July\year 1983\endref\ref{X.400}\book Message Handling Systems: System Model-Service Elements\bookinfo Recommendation X.400\publ International Telegraph and Telephone Consultative Committee (CCITT)\endref\endreferences