[Mimedefang] accept, then scan?

[Andy Lyttle]

Question:

As I understood it, once we've accepted HELO, RCPT FROM, MAIL TO and  
gotten to the DATA part, we're committed to delivering the message  
and cannot change our minds and reject it after we get to look at the  
headers or body.  However, it looks like connecting MTAs are waiting  
for an acknowledgment that the message has been successfully received  
after they've delivered the message contents, so maybe that isn't  
entirely true?  Anyway, if it is true, what I'd like to do is to  
accept the message, close the connection, and THEN scan the message  
with SpamAssassin.  Is that possible?  The reason is, on old slow  
hardware, certain large messages are taking too long to scan (two  
minutes or more), and in some cases I'm accepting the message but the  
sending MTA timed out, so I wind up receiving duplicate messages.  In  
other cases, Sendmail just times out because mimedefang took too long  
to respond, so Sendmail returning a tempfail.

I'll be upgrading the hardware at the end of next month.  What are  
some ideas until then?

SpamAssassin scans most messages in only a second or two.

~ Andy