A typical SMTP session with timing in 20m/s incerements:

----------------------
Sent: 7 Bytes: EHLO
 20m/s
 40m/s
 60m/s
 80m/s
Rply: 148 Bytes: 250-mx.google.com at your service, [71.331.441.11]
250-SIZE 35651584
250-8BITMIME
250-AUTH LOGIN PLAIN
250-ENHANCEDSTATUSCODES
250 PIPELINING

----------------------
Sent: 13 Bytes: AUTH LOGIN
 20m/s
 40m/s
 60m/s
 80m/s
Rply: 18 Bytes: 334 VXNlcm5hbWU6

----------------------
Sent: 46 Bytes: bm9yZXBseUBmb3JlY2xvc3VyZXF3aWt2aWV3LmNvbQ==
 20m/s
 40m/s
 60m/s
 80m/s
Rply: 18 Bytes: 334 UGFzc3dvcmQ6

----------------------
Sent: 14 Bytes: aXJvbndpbGw=
 20m/s
 40m/s
 60m/s
 80m/s
 100m/s
 120m/s
 140m/s
 160m/s
 180m/s
 200m/s
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 240m/s
 260m/s
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 320m/s
 340m/s
 360m/s
 380m/s
 400m/s
Rply: 20 Bytes: 235 2.7.0 Accepted

----------------------
Sent: 46 Bytes: MAIL FROM: <noreply@mydomain.com>
 20m/s
 40m/s
 60m/s
 80m/s
Rply: 30 Bytes: 250 2.1.0 OK 8sm665581yxb.25

----------------------
Sent: 29 Bytes: RCPT TO: <you@yourdomain.com>
 20m/s
 40m/s
 60m/s
 80m/s
Rply: 30 Bytes: 250 2.1.5 OK 8sm665581yxb.25

----------------------
Sent: 7 Bytes: DATA
 20m/s
 40m/s
 60m/s
 80m/s
 100m/s
 120m/s
 140m/s
 160m/s
 180m/s
 200m/s
 220m/s
Rply: 31 Bytes: 354  Go ahead 8sm665581yxb.25

----------------------
Sent: 176 Bytes: Date: Fri, 20 Nov 2009 01:05:50 -0800
 20m/s
 40m/s
 60m/s
 80m/s
 100m/s
 120m/s
 140m/s
 160m/s
 180m/s
 200m/s
 220m/s
 240m/s
 260m/s
 280m/s
 300m/s
 320m/s
 340m/s
 360m/s
 380m/s
 400m/s
 420m/s
Rply: 41 Bytes: 250 2.0.0 OK 1258707959 8sm665581yxb.25

----------------------
Sent: 7 Bytes: QUIT
 20m/s
 40m/s
 60m/s
 80m/s
Rply: 46 Bytes: 221 2.0.0 closing connection 8sm665581yxb.25

----------------------

for a grant total of 1520m/s (1.5 seconds)






Compared to a PIPELINED session:

Sent: 7 Bytes: EHLO
 20m/s
 40m/s
 60m/s
 80m/s
Rply: 148 Bytes:
250-mx.google.com at your service, [76.201.141.16]
250-SIZE 35651584
250-8BITMIME
250-AUTH LOGIN PLAIN
250-ENHANCEDSTATUSCODES
250 PIPELINING

----------------------
Sent: 73 Bytes: AUTH LOGIN
 20m/s
 40m/s
 60m/s
 80m/s
Rply: 36 Bytes:
334 VXNlcm5hbWU6
334 UGFzc3dvcmQ6

----------------------
Sent: 75 Bytes: 
MAIL FROM: <noreply@mydomain.com>
RCPT TO: <you@yourdomain.com>
 20m/s
 40m/s
 60m/s
 80m/s
Rply: 80 Bytes:
235 2.7.0 Accepted
250 2.1.0 OK 4sm967231yxd.16
250 2.1.5 OK 4sm967231yxd.16

----------------------
Sent: 183 Bytes: DATA
 20m/s
 40m/s
 60m/s
 80m/s
 100m/s
 120m/s
 140m/s
 160m/s
 180m/s
 200m/s
 220m/s
Rply: 31 Bytes:
354  Go ahead 4sm967231yxd.16

 20m/s
 40m/s
 60m/s
 80m/s
 100m/s
 120m/s
 140m/s
 160m/s
 180m/s
 200m/s
 220m/s
 240m/s
 260m/s
 280m/s
 300m/s
 320m/s
 340m/s
Rply: 41 Bytes:
250 2.0.0 OK 1258761969 4sm967231yxd.16

----------------------
Sent: 7 Bytes: QUIT
 20m/s
 40m/s
 60m/s
 80m/s
Rply: 46 Bytes:
221 2.0.0 closing connection 4sm967231yxd.16


For a total of 880m/s, about half the time.