Greylisting

Vernon Schryver vjs@calcite.rhyolite.com
Wed Dec 7 19:29:32 UTC 2005


> From: "Ugo Bellavance" 

> >> set in "learning mode", meaning that it sees traffic going on, adds

> > However, in practice, this is useless.  If your correspondents' mail
> > systems don't retry when you first turn on greylisting, then they
> > won't retry after a long hiatus.
>
> It is only to reduce the delays that I would do that. 

Again, if the greylist delays are bad now, they'll be bad 6 months from
now when a correspondent changes IP addresses or comes back from vacation.
If you can tolerate the trivial (in my view) delays of greylisting in
the long run, you'll not notice them now when starting.

Many users are past irrational to just plain kooky about greylist
delays, which is why I agreed with ISPs to add the "option greylist-log-off"
mechanism for whiteclnt files.  (See the dcc man page.)  It's kooky to
get excited about what is almost always a matter of a extra minutes in
the delivery of mail that are almost never noticed when the logging is
turned off.


>                                                        While talking
> about delays, what are the delays to be expected?  Do most SMTP client
> retry after 10 seconds, 15 min, 30 min?

RFC 2821 says they "SHOULD" retry after 30 minutes.  However,
no one can say what most SMTP clients might do without a definition
of "most."  Do you mean most mail senders, most mail messages, most
installations, or most implementations?  Do you care about any of those
for the whole world or just the people who might send mail to you?


> >> To help the process, I guess I only have to add entries to
> >> /var/dcc/whitelist? 
> > 
> > yes, you can whitelist senders.
>
> Ok, so an entry on the whitelist will not be subject to delay, but will
> it also disable regular DCC checks for this entry?

Entries in /var/dcc/grey_whitelist affect only greylisting, but do not
take effect until you run `dbclean -G on`.
Entries in /var/dcc/whiteclnt affect everything.
You can also use the mechanism based on dccsight used by the CGI scripts
to force the addition of a greylist triple to the database from a log file.


Vernon Schryver    vjs@rhyolite.com



More information about the DCC mailing list

Contact vjs@rhyolite.com by mail or use the form.