Step 1 -- Source Host to Relay Host 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 Step 2 -- Relay Host to Destination Host 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 Scenario 3