Re: [mailop] Greylisting never passing on retry
On 2021-04-20 03:24, Hans-Martin Mosner via mailop wrote: Another possibility, which would for example apply to the mail systems for which I'm responsible, is that temp rejection is used to defer mail from questionable sources until a manual check shows that they're likely genuine (or in some cases, until a rbl hit indicates that others received the mail and categorized it as spam). In this case, we wouldnt talk about greylisting in the error message, though, as that is misleading. Never hurts to remember that some of us are jerks when it comes to providing clues to spammers too. Back when I was running a small hosting company I would try to report the least significant DNSBL hit in the rejection message when in reality there was a more complex scoring system at play, and resolving that listing would do nothing more than give you a new (but also valid) DNSBL hit on your next attempt. It wasn't misleading, technically, but by the time an IP tripped the scoring system to an outright reject before even seeing the message body it was pretty certain they were living in a sewer anyway, so why not let senders work their way up? There was also a link to generate a whitelisting request for the odd bit of legitimate mail. ___ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
Re: [mailop] Greylisting never passing on retry
Aside from the possibility that the message is simply wrong, or the implementation broken, is your mail server acting like most other servers when presented with a failure (soft or hard)? Your posting seems to be that you give up after the second try. Most servers will try at least 5 times for such, only giving up after hours (sendmail defaults at 4 days). In fact, if you're giving up in a unusually low number of retries (like just one), that may cause your IP to be penalized in some way - increasing retries you need to do OR outright blacklisting - but getting a 4xx simply because the code handling greylisting only answers in one way, and the permanently blocked by the greylisting code gets the same answer as greglisting proceeding as intended. On 2021-04-20 05:06, Neil Youngman via mailop wrote: > I have observed that messages from our system are temporarily rejected > as greylisted by one destination but they are never accepted on retry. > The response is logged as "DATA: 451 0.0.0 1 recipients being greylisted > for 5 minutes". We retry after 10 minutes and get the same response. > > Normally I would expect the retries to pass greylisting. Does anyone have > any insight into why this is not behaving as expected? The destination is > exeter.ac.uk. > > Neil Youngman > > > ___ > mailop mailing list > mailop@mailop.org > https://list.mailop.org/listinfo/mailop > ___ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
Re: [mailop] Greylisting never passing on retry
Neil Youngman via mailop (Di 20 Apr 2021 11:06:10 CEST):
> I have observed that messages from our system are temporarily rejected
> as greylisted by one destination but they are never accepted on retry.
> The response is logged as "DATA: 451 0.0.0 1 recipients being greylisted
> for 5 minutes". We retry after 10 minutes and get the same response.
That is 451 as the response to the "DATA" command? Or to the final dot, after
the DATA beeing sent?
The mentioned 1 recipient was the only recipient? Then I'd ask why they
do not reject the individual recipient with 4xx already at the RCPT
phase, or, if they do, why - after having a rejected recipient, your
server tries to send DATA.
In case they're greylisting after the final dot, make sure that not only
the IP, the sender, and the recipients list are identical to the first
attempt, but also the DATA (header+body) of your message.
I think, this will be difficult, if possible at all. Depends on *your*
mailsystem. And of course on their processing of the header+body.
Best regards from Dresden/Germany
Viele Grüße aus Dresden
Heiko Schlittermann
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Re: [mailop] Greylisting never passing on retry
On 20/04/2021 10:06, Neil Youngman via mailop wrote: I have observed that messages from our system are temporarily rejected as greylisted by one destination but they are never accepted on retry. The response is logged as "DATA: 451 0.0.0 1 recipients being greylisted for 5 minutes". We retry after 10 minutes and get the same response. Normally I would expect the retries to pass greylisting. Does anyone have any insight into why this is not behaving as expected? The destination is exeter.ac.uk. exeter.ac.uk's email administrator is probably the only one who can say for certain. Anything else is a guess. Make sure the retried message is from exactly the same return path email address AND IP address as the originally tried message. If either of these is different, the receiving server could think that it's a new message, so it will start a new greylist delay for that message. Paul -- Paul Smith Computer Services Tel: 01484 855800 Vat No: GB 685 6987 53 Sign up for news & updates at http://www.pscs.co.uk/go/subscribe ___ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
Re: [mailop] Greylisting never passing on retry
Am 20.04.21 um 11:06 schrieb Neil Youngman via mailop: > I have observed that messages from our system are temporarily rejected > as greylisted by one destination but they are never accepted on retry. > The response is logged as "DATA: 451 0.0.0 1 recipients being greylisted > for 5 minutes". We retry after 10 minutes and get the same response. > > Normally I would expect the retries to pass greylisting. Does anyone have > any insight into why this is not behaving as expected? The destination is > exeter.ac.uk. > > Neil Youngman The exeter.ac.uk postmaster is probably the only one who can tell you what really happens, but as with all spam-reducing heuristics it is quite possible that this system is somehow broken. Another possibility, which would for example apply to the mail systems for which I'm responsible, is that temp rejection is used to defer mail from questionable sources until a manual check shows that they're likely genuine (or in some cases, until a rbl hit indicates that others received the mail and categorized it as spam). In this case, we wouldnt talk about greylisting in the error message, though, as that is misleading. Cheers, Hans-Martin ___ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
[mailop] Greylisting never passing on retry
I have observed that messages from our system are temporarily rejected as greylisted by one destination but they are never accepted on retry. The response is logged as "DATA: 451 0.0.0 1 recipients being greylisted for 5 minutes". We retry after 10 minutes and get the same response. Normally I would expect the retries to pass greylisting. Does anyone have any insight into why this is not behaving as expected? The destination is exeter.ac.uk. Neil Youngman ___ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
