S: QUIT

R: 221 MIT-Multics.ARPA Service closing transmission channel

轉發郵件 

第一步：源主機到轉發主機

R: 220 USC-ISIE.ARPA Simple Mail Transfer Service Ready

S: HELO MIT-AI.ARPA

R: 250 USC-ISIE.ARPA

　

S: MAIL FROM:<JQP@MIT-AI.ARPA>

R: 250 OK

S: RCPT TO:<@USC-ISIE.ARPA:Jones@BBN-VAX.ARPA>

R: 250 OK

S: DATA

R: 354 Start mail input; end with <CRLF>.<CRLF>

S: Date: 2 Nov 81 22:33:44

S: From: John Q. Public <JQP@MIT-AI.ARPA>

S: Subject: The Next Meeting of the Board

S: To: Jones@BBN-Vax.ARPA

S:

S: Bill:

S: The next meeting of the board of directors will be

S: on Tuesday.

S: John.

S: .

R: 250 OK

S: QUIT

R: 221 USC-ISIE.ARPA Service closing transmission channel

第二步：轉發主機到目的主機

R: 220 BBN-VAX.ARPA Simple Mail Transfer Service Ready

S: HELO USC-ISIE.ARPA

R: 250 BBN-VAX.ARPA

S: MAIL FROM:<@USC-ISIE.ARPA:JQP@MIT-AI.ARPA>

R: 250 OK

S: RCPT TO:<Jones@BBN-VAX.ARPA>

R: 250 OK

S: DATA

R: 354 Start mail input; end with <CRLF>.<CRLF>

S: Received: from MIT-AI.ARPA by USC-ISIE.ARPA ;

2 Nov 81 22:40:10 UT

S: Date: 2 Nov 81 22:33:44

S: From: John Q. Public <JQP@MIT-AI.ARPA>

S: Subject: The Next Meeting of the Board

S: To: Jones@BBN-Vax.ARPA

S:

S: Bill:

S: The next meeting of the board of directors will be

S: on Tuesday.

S: John.

S: .

R: 250 OK

S: QUIT

R: 221 USC-ISIE.ARPA Service closing transmission channel
確認和發送

R: 220 SU-SCORE.ARPA Simple Mail Transfer Service Ready

S: HELO MIT-MC.ARPA

R: 250 SU-SCORE.ARPA

S: VRFY Crispin

R: 250 Mark Crispin <Admin.MRC@SU-SCORE.ARPA>

S: SEND FROM:<EAK@MIT-MC.ARPA>

R: 250 OK

S: RCPT TO:<Admin.MRC@SU-SCORE.ARPA>

R: 250 OK
S: DATA

R: 354 Start mail input; end with <CRLF>.<CRLF>

S: Blah blah blah...

S: ...etc. etc. etc.

S: .

R: 250 OK

S: QUIT

R: 221 SU-SCORE.ARPA Service closing transmission channel

獲得和發送郵件 首先確定用戶名，然后嘗試將郵件發送到用戶終端，當它失敗時，發送到用戶郵箱。

R: 220 SU-SCORE.ARPA Simple Mail Transfer Service Ready

S: HELO MIT-MC.ARPA

R: 250 SU-SCORE.ARPA

　

S: VRFY Crispin

R: 250 Mark Crispin <Admin.MRC@SU-SCORE.ARPA>

S: SEND FROM:<EAK@MIT-MC.ARPA>

R: 250 OK
S: RCPT TO:<Admin.MRC@SU-SCORE.ARPA>

R: 450 User not active now

S: RSET

R: 250 OK

S: MAIL FROM:<EAK@MIT-MC.ARPA>

R: 250 OK

S: RCPT TO:<Admin.MRC@SU-SCORE.ARPA>

R: 250 OK

S: DATA

R: 354 Start mail input; end with <CRLF>.<CRLF>

S: Blah blah blah...

S: ...etc. etc. etc.

S: .

R: 250 OK

S: QUIT

R: 221 SU-SCORE.ARPA Service closing transmission channel

上述問題的更有效的作法 

R: 220 SU-SCORE.ARPA Simple Mail Transfer Service Ready

S: HELO MIT-MC.ARPA

R: 250 SU-SCORE.ARPA
S: VRFY Crispin

R: 250 Mark Crispin <Admin.MRC@SU-SCORE.ARPA>

S: SOML FROM:<EAK@MIT-MC.ARPA>

R: 250 OK

S: RCPT TO:<Admin.MRC@SU-SCORE.ARPA>

R: 250 User not active now, so will do mail.

S: DATA

R: 354 Start mail input; end with <CRLF>.<CRLF>

S: Blah blah blah...

S: ...etc. etc. etc.

S: .

R: 250 OK

S: QUIT

R: 221 SU-SCORE.ARPA Service closing transmission channel

　　郵件列表 首先，兩個郵件列表中的每一個在不同主機的不同會話上擴展，然后，通過轉發主機向列表上的用戶發送郵件。

第一步：擴展第一個列表

R: 220 MIT-AI.ARPA Simple Mail Transfer Service Ready

S: HELO SU-SCORE.ARPA

R: 250 MIT-AI.ARPA

　

S: EXPN Example-People

R: 250-<ABC@MIT-MC.ARPA>

R: 250-Fred Fonebone <Fonebone@USC-ISIQ.ARPA>

R: 250-Xenon Y. Zither <XYZ@MIT-AI.ARPA>

R: 250-Quincy Smith <@USC-ISIF.ARPA:Q-Smith@ISI-VAXA.ARPA>

R: 250-<joe@foo-unix.ARPA>

R: 250 <xyz@bar-unix.ARPA>

S: QUIT

R: 221 MIT-AI.ARPA Service closing transmission channel
　
第二步：擴展第二個列表 

R: 220 MIT-MC.ARPA Simple Mail Transfer Service Ready 

S: HELO SU-SCORE.ARPA

R: 250 MIT-MC.ARPA

S: EXPN Interested-Parties

R: 250-Al Calico <ABC@MIT-MC.ARPA>

R: 250-<XYZ@MIT-AI.ARPA>

R: 250-Quincy Smith <@USC-ISIF.ARPA:Q-Smith@ISI-VAXA.ARPA>

R: 250-<fred@BBN-UNIX.ARPA>

R: 250 <xyz@bar-unix.ARPA>

S: QUIT

R: 221 MIT-MC.ARPA Service closing transmission channel

　

第三步：通過轉發主機向包括于兩個列表中的所有用戶發送郵件 

R: 220 USC-ISIE.ARPA Simple Mail Transfer Service Ready

S: HELO SU-SCORE.ARPA

R: 250 USC-ISIE.ARPA

S: MAIL FROM:<Account.Person@SU-SCORE.ARPA>

R: 250 OK

S: RCPT TO:<@USC-ISIE.ARPA:ABC@MIT-MC.ARPA>

R: 250 OK

S: RCPT TO:<@USC-ISIE.ARPA:Fonebone@USC-ISIQA.ARPA>

R: 250 OK

S: RCPT TO:<@USC-ISIE.ARPA:XYZ@MIT-AI.ARPA>

R: 250 OK

S: RCPT

TO:<@USC-ISIE.ARPA,@USC-ISIF.ARPA:Q-Smith@ISI-VAXA.ARPA>