RFC 1123 (http://www.ietf.org/rfc/rfc1123.txt)
5.3.1.1 Sending Strategy The general model of a sender-SMTP is one or more processes that periodically attempt to transmit outgoing mail. In a typical system, the program that composes a message has some method for requesting immediate attention for a new piece of outgoing mail, while mail that cannot be transmitted immediately MUST be queued and periodically retried by the sender. A mail queue entry will include not only the message itself but also the envelope information. The sender MUST delay retrying a particular destination after one attempt has failed. In general, the retry interval SHOULD be at least 30 minutes; however, more sophisticated and variable strategies will be beneficial when the sender-SMTP can determine the reason for non- delivery. Retries continue until the message is transmitted or the sender gives up; the give-up time generally needs to be at least 4-5 days. The parameters to the retry algorithm MUST be configurable. Cheers, Phil -- Phil Randal Network Engineer Herefordshire Council Hereford, UK > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > Sent: 23 November 2006 06:57 > To: users@spamassassin.apache.org > Subject: Re: Greylisting > > Philip Prindeville wrote: > > Don't they? I thought the recommended retry time was 2 minutes, > > doubling on each failure, and maxing out at 2 hours. > > The traditional Sendmail would retry either every 15 or every 30 > minutes. This would almost always be seen as the command line setting > as sendmail -q30m. But this may have changed in recent Sendmail > releases. I just checked a stock RHEL4 system and the queue retry > time by default there is 1h. So from such a system a greylisting > would delay the initial message by 1h. Subsequent messages would pass > without delay. > > Bob >