Heron wrote: > I have pointed out that some SMTP servers in the world reject incoming > e-mails for the first time with a "temporary error" message. If the message > comes second time it is accepted. > This mechanism is used to reject many spams, since many spam sending > computers do not try to send the message again after receiving "temporary > error" message from the remote SMTP server. > > My question is - how to implement such mechanism in Exim 4.x ?
It's called grey listing. I use greylstd from http://greylstd.cmeerw.org, the relevant exim.conf part is: # Greylisting defer message = Greylisting in effect, please try again later. log_message = greylisted. domains = +local_domains : +relay_to_domains !senders = : [EMAIL PROTECTED] !hosts = +relay_from_hosts !authenticated = * condition = ${if eq {${readsocket{/var/run/greylstd/greylstd.sock} {check $sender_host_address $sender_address [EMAIL PROTECTED] er}{true}{false}} The time is something you adjust to your liking, 5 minutes is not unusual, even if some servers do retry fast at the start then fall back to a more usual 15 minutes retry cycle. -- René Berber -- ## List details at http://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
