delaying mail before passing to next hop
hi- short version: i have an mx which, after doing the initial handling [postscreen, etc] of messages arriving from the internet, relays mail to another computer for content filtering [amavis/spamassassin]: relay_transport = lmtp-filter:[mfa.example.com]:lmtp-filter-external after a message has been accepted, i'd like to delay its relay to the content filter for five minutes. can postfix do this? longer version: i've noticed a recent trend in which a message arrives, passes postscreen/various smtpd_*_restrictions, and is passed to the content filter, which passes it as clean, having not matched many rules [in particular, network tests like uri dnsbls, razor/pyzor, etc]. minutes later, the same message arrives [timestamps, message ids, etc differ], in that time has made its way into the results of various network tests, and is then marked is spam. e.g. my consideration for this approach. i'd also be interested in general thoughts on this problem, and other possibilities. i'm not particularly fond of artificial delays, and the various implications [e.g. queue sizes, user expectations, etc], but in the context of a controlled environment [e.g. after postfix has accepted the message, i'm willing to at least entertain the possibility. thanks-ben
Re: delaying mail before passing to next hop
Am 13.11.2014 um 18:14 schrieb b...@bitrate.net: hi- short version: i have an mx which, after doing the initial handling [postscreen, etc] of messages arriving from the internet, relays mail to another computer for content filtering [amavis/spamassassin]: relay_transport = lmtp-filter:[mfa.example.com]:lmtp-filter-external after a message has been accepted, i'd like to delay its relay to the content filter for five minutes. can postfix do this? longer version: i've noticed a recent trend in which a message arrives, passes postscreen/various smtpd_*_restrictions, and is passed to the content filter, which passes it as clean, having not matched many rules [in particular, network tests like uri dnsbls, razor/pyzor, etc]. minutes later, the same message arrives [timestamps, message ids, etc differ], in that time has made its way into the results of various network tests, and is then marked is spam. e.g. my consideration for this approach. i'd also be interested in general thoughts on this problem, and other possibilities. i'm not particularly fond of artificial delays, and the various implications [e.g. queue sizes, user expectations, etc], but in the context of a controlled environment [e.g. after postfix has accepted the message, i'm willing to at least entertain the possibility. thanks-ben interesting, didnt notice such yet you might hold mail, and release it by cron etc Best Regards MfG Robert Schetterer -- [*] sys4 AG http://sys4.de, +49 (89) 30 90 46 64 Franziskanerstraße 15, 81669 München Sitz der Gesellschaft: München, Amtsgericht München: HRB 199263 Vorstand: Patrick Ben Koetter, Marc Schiffbauer Aufsichtsratsvorsitzender: Florian Kirstein
Re: delaying mail before passing to next hop
On 11/13/2014 11:14 AM, b...@bitrate.net wrote: hi- short version: i have an mx which, after doing the initial handling [postscreen, etc] of messages arriving from the internet, relays mail to another computer for content filtering [amavis/spamassassin]: relay_transport = lmtp-filter:[mfa.example.com]:lmtp-filter-external after a message has been accepted, i'd like to delay its relay to the content filter for five minutes. can postfix do this? longer version: i've noticed a recent trend in which a message arrives, passes postscreen/various smtpd_*_restrictions, and is passed to the content filter, which passes it as clean, having not matched many rules [in particular, network tests like uri dnsbls, razor/pyzor, etc]. minutes later, the same message arrives [timestamps, message ids, etc differ], in that time has made its way into the results of various network tests, and is then marked is spam. e.g. my consideration for this approach. i'd also be interested in general thoughts on this problem, and other possibilities. i'm not particularly fond of artificial delays, and the various implications [e.g. queue sizes, user expectations, etc], but in the context of a controlled environment [e.g. after postfix has accepted the message, i'm willing to at least entertain the possibility. thanks-ben This is exactly why greylisting was invented. Have you tried that? -- Noel Jones
Re: delaying mail before passing to next hop
On Nov 13, 2014, at 1:02 PM, Noel Jones njo...@megan.vbhcs.org wrote: This is exactly why greylisting was invented. Have you tried that? Greylisting has a host of problems of its own though. Even with a dedicated mail admin who is really trying to keep up on all the mail coming in, you *will* lose mail with greylisting. -- Otto: Apes don't read philosophy. Wanda: Yes, they do Otto, they just don't understand it.
Re: delaying mail before passing to next hop
On Nov 13, 2014, at 15.02, Noel Jones njo...@megan.vbhcs.org wrote: On 11/13/2014 11:14 AM, b...@bitrate.net wrote: hi- short version: i have an mx which, after doing the initial handling [postscreen, etc] of messages arriving from the internet, relays mail to another computer for content filtering [amavis/spamassassin]: relay_transport = lmtp-filter:[mfa.example.com]:lmtp-filter-external after a message has been accepted, i'd like to delay its relay to the content filter for five minutes. can postfix do this? longer version: i've noticed a recent trend in which a message arrives, passes postscreen/various smtpd_*_restrictions, and is passed to the content filter, which passes it as clean, having not matched many rules [in particular, network tests like uri dnsbls, razor/pyzor, etc]. minutes later, the same message arrives [timestamps, message ids, etc differ], in that time has made its way into the results of various network tests, and is then marked is spam. e.g. my consideration for this approach. i'd also be interested in general thoughts on this problem, and other possibilities. i'm not particularly fond of artificial delays, and the various implications [e.g. queue sizes, user expectations, etc], but in the context of a controlled environment [e.g. after postfix has accepted the message, i'm willing to at least entertain the possibility. thanks-ben This is exactly why greylisting was invented. Have you tried that? i don't know about exactly, but yes, i did briefly consider that greylisting would have a somewhat similar effect. it would introduce a delay, but at the cost of all of the other side effects of greylisting, which would likely cause more problems than it would solve, imho. that's why i wanted to do it after the message was accepted, where the onus can be fully on me regarding its fate. -ben
Re: delaying mail before passing to next hop
On Nov 13, 2014, at 13.00, Robert Schetterer r...@sys4.de wrote: Am 13.11.2014 um 18:14 schrieb b...@bitrate.net: hi- short version: i have an mx which, after doing the initial handling [postscreen, etc] of messages arriving from the internet, relays mail to another computer for content filtering [amavis/spamassassin]: relay_transport = lmtp-filter:[mfa.example.com]:lmtp-filter-external after a message has been accepted, i'd like to delay its relay to the content filter for five minutes. can postfix do this? longer version: i've noticed a recent trend in which a message arrives, passes postscreen/various smtpd_*_restrictions, and is passed to the content filter, which passes it as clean, having not matched many rules [in particular, network tests like uri dnsbls, razor/pyzor, etc]. minutes later, the same message arrives [timestamps, message ids, etc differ], in that time has made its way into the results of various network tests, and is then marked is spam. e.g. my consideration for this approach. i'd also be interested in general thoughts on this problem, and other possibilities. i'm not particularly fond of artificial delays, and the various implications [e.g. queue sizes, user expectations, etc], but in the context of a controlled environment [e.g. after postfix has accepted the message, i'm willing to at least entertain the possibility. thanks-ben interesting, didnt notice such yet you might hold mail, and release it by cron etc thanks - cron came to mind initially for me too. i wondered though if postfix might offer a mechanism of its own.
