I've implemented Greylisting on a test server. I had a look and
initially found this:
http://www.mimedefang.org/kwiki/index.cgi?GreyListiningSQLite
Which got me off to a great start, but then I had a look at what it was
doing and was somewhat confused... This code seems to delete the entry
from the database right after a successful email transaction (ie. one that
got 451'd, waitied then was sent successfully).
I'm not sure this is right... If so, it would seem that when someone sent
a second email from/to the same addresses then it would get blocked again
for 10 minutes.
And I couldn't work out what it was doing with the messageid - but (feel
free to correct me on this!) maybe it's not a message id, as that's not
actually been transmitted into the system by the point...
So I changed it round a bit...
The first thing I did was to store the timestamp as an unsigned integer. I
guess this might make it go a bit faster. I hate textual timestamp
handling, give me a time_t every time... Maybe I'm missing something here,
but it seems to make arithmetic and comparisons easier too...
Now, I just store the triple and a timestamp (of now + 10 miuntes), then
when I see the triple again, I continue to 451 it until now >= stored
timestamp.
At that point, I set the timestamp to 0 which efectively whitelists it
forever and let it through. (Although I'm considering keeping a count)
Is this a good thing to do?
I still have a reaper process which purges entries from the database if
it hasn't been "used" for over a day.
And well, so-far so good, but I'd appreciate any comments about my
methods...
My code is at: http://www.drogon.net/greylisting/ for anyone who cares!
Thanks,
Gordon
Ps. It's quite depressing looking at the stats - I'm seeing over 96% of
messages through the test server as greylist failures - ie. spam )-:
_______________________________________________
NOTE: If there is a disclaimer or other legal boilerplate in the above
message, it is NULL AND VOID. You may ignore it.
Visit http://www.mimedefang.org and http://www.roaringpenguin.com
MIMEDefang mailing list [email protected]
http://lists.roaringpenguin.com/mailman/listinfo/mimedefang
