Re: slow email validation problems (was reject vs bounce)

--On 13. september 2005 10:09 +0100 Paul Smith 
<paul(_at_)pscs(_dot_)co(_dot_)uk> wrote:

> We're trying to decide what to do about this. The 'easiest' thing to do
> is to accept the message if it's going to take over 30 seconds to
> process, and generate a 'bounce' later if necessary - but I don't like
> that because of faked sender addresses.
>
> I guess other people here have had the same sort of problems, so are
> there any better alternatives?
>
> I'm thinking of generating '250-please wait' multiline response lines
> every 30 seconds or so whilst the message is being processed, with a
> final '250 OK' or '550 message rejected because of ...' line.
hmm.... "scaling is the ultimate problem", says Mike O'Dell.

If you take 30 seconds to accept a message, and have the default Postfix 
process limit of 100, you can accept up to 300 messages a minute - or an 
average of 5 per second.
If you do this, and others follow your example, you're imposing a limit on 
the SENDING MTA of 5 messages per second (if it's Postfix).
If you have large resources on the sending side, you can open up 
connections until you run out of process descriptors, port numbers of 
something else - but it's a heavy demand on a busy mail system to increase 
the average transaction time from sub-seconds to more than 30 seconds.
I hope most of the recipient MTAs for IETF mail don't do this.

                 Harald

pgphE8bfChMya.pgp
Description: PGP signature