anti-spam error number return code not consistent?

["Paquette, Trevor" <TrevorPaquette@mcc.net>]

Just noticed this as well:

Look at the error numbers from LOG1 and LOG2. Why are the error numbers
different?
IE: 553-5.7.1 vs 453-4.7.1

LOG1:
7615#   connection from [209.136.134.6] ident: root [port 3354]
7615w   220 gate ZMailer Server 2.99.49p8 #1 ESMTP+IDENT ready at Sun,
16 Nov 1997 18:54:31 -0700
7615#   remote from [209.136.134.6]
7615r   EHLO olma.net
7615w   250-gate Hello olma.net
7615w   250-SIZE 0
7615w   250-8BITMIME
7615w   250-PIPELINING
7615w   250-CHUNKING
7615w   250-ENHANCEDSTATUSCODES
7615w   250-EXPN
7615w   250-VRFY
7615w   250-DSN
7615w   250-X-RCPTLIMIT 10000
7615w   250-ETRN
7615w   250 HELP
7615r   MAIL From:<tobesuccessful@spica.net> SIZE=1988
7615w   553-5.7.1 Access denied due to excessive spamming from your
domain
7615w   553-5.7.1 or address.  If you are a customer of a spam-friendly
ISP,
7615w   553-5.7.1 we recommend changing to a different ISP.
7615w   553-5.7.1 
7615w   553 5.7.1 We apologize for the inconvenience.



LOG2:
7715#   connection from ns1.econnect.ca ident: NO-IDENT-SERVICE [port
4624]
7715w   220 gate ZMailer Server 2.99.49p8 #1 ESMTP+IDENT ready at Sun,
16 Nov 1997 19:24:56 -0700
7715#   remote from [206.186.50.33]
7715r   EHLO ns1.econnect.ca
7715w   250-gate Hello ns1.econnect.ca
7715w   250-SIZE 0
7715w   250-8BITMIME
7715w   250-PIPELINING
7715w   250-CHUNKING
7715w   250-ENHANCEDSTATUSCODES
7715w   250-EXPN
7715w   250-VRFY
7715w   250-DSN
7715w   250-X-RCPTLIMIT 10000
7715w   250-ETRN
7715w   250 HELP
7715r   MAIL From:<riscalla@ns3.econnect.ca> SIZE=1729
7715w   453-4.7.1 Access denied due to excessive spamming from your
domain
7715w   453-4.7.1 or address.  If you are a customer of a spam-friendly
ISP,
7715w   453-4.7.1 we recommend changing to a different ISP.
7715w   453-4.7.1 
7715w   453 4.7.1 We apologize for the inconvenience.
7715r   QUIT