Greylisting rejection unexplained

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Greylisting rejection unexplained

Postby sabbatini » Wed Jun 10th, 2015 7:28am

Mailtraq Version: 2.17.6.3398

Mail from a sender who has sent before started to be rejected under greylisting: Have put sender and recipient on white list, but still rejection. I think it is the sending host as it never sends data, but need to be sure to assure my user our mail system is correct.

Logs read as follows:

Before whitelist:

00000001 00012063 10/06/2015 10:56:20 Greylisting: (spf=not-implemented fcrdns=present dbl=low-score mx=not-found) Rejecting (ip=157.56.112.55,from=xxxxx@xxxx.co.uk,rcpt=xxx@xxxxx-xxxxx.com) for another 15 seconds
00000001 00012063 10/06/2015 10:56:20 RCPT TO:<xxx@xxxxxx-xxxxx.com> ---> 451 greylisted (try again in 15 seconds)
00000001 00012063 10/06/2015 10:56:20 QUIT ---> 221 have a nice day (SMTP Closing)
00000001 00012063 10/06/2015 10:56:20 SMTP Client Disconnected (157.56.112.55): No DATA
- 00012063

After whitelist:

00000001 0001210F 10/06/2015 11:55:42 Sender Whitelist: Matched xxxx@xxxxxxxxx.co.uk
00000001 0001210F 10/06/2015 11:55:42 MAIL FROM:<xxxxx@xxxxxxxxx.co.uk> SIZE=575832 ---> 250 receiving from xxxxxxx@xxxxxxxxx.co.uk
00000001 0001210F 10/06/2015 11:55:42 Recipient Whitelist: Matched xxx@xxxxxx-xxxxx.com
x
x
x
00000001 0001210F 10/06/2015 11:55:54 Greylisting: (spf=not-implemented fcrdns=present dbl=low-score mx=not-found) Rejecting (ip=157.55.234.91,from=xxxxx@xxxxxxxx.co.uk,rcpt=xxx@xxx-xxxx.com) for another 15 seconds
00000001 0001210F 10/06/2015 11:55:54 RCPT TO:<xxx@xxxxxx-xxxxxx.com> ---> 451 greylisted (try again in 15 seconds)
00000001 0001210F 10/06/2015 11:55:55 QUIT ---> 221 have a nice day (SMTP Closing)
00000001 0001210F 10/06/2015 11:55:55 SMTP Client Disconnected (157.55.234.91): No DATA
- 0001210F

Many thanks
sabbatini
 
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Re: Greylisting rejection unexplained

Postby Martin Clayton » Wed Jun 10th, 2015 12:03pm

Did you whitelist under SMTP service -> Blacklists -> Greylist -> Senders|Recipients (i.e., not just SMTP service -> Blacklists -> White Lists -> Senders|Recipients) ?

I expect the mail would get through eventually - when the (ip + sender + recipient) triplet matches a previous recent delivery attempt.
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Re: Greylisting rejection unexplained

Postby sabbatini » Thu Jun 11th, 2015 8:39am

Thanks for the reply. I requested the sender send a test e-mail and it came through no problem. Then got sender to send the content of the e-mail in question as a new mail and it made it through as well. I can only conclude that the original e-mail was in someway either corrupt or contained something suspcious.
sabbatini
 
Posts: 20
Joined: Mon Mar 07th, 2011 7:27am

Re: Greylisting rejection unexplained

Postby Martin Clayton » Thu Jun 11th, 2015 10:55am

sabbatini wrote:I can only conclude that the original e-mail was in someway either corrupt or contained something suspcious.

The logs suggest otherwise; on the greylisting 451 (come back later) the sender attempts to re-send from a number of new ip addresses. Each of these addresses is stored by Mailtraq's Greylist Manager. When they eventually send from an ip address that's been seen before, Mailtraq accepts the message and whitelists the ip address. The two test messages probably sailed through because the Greylist Manager recognised the ip/sender/recipient triplet.

A better test would be to shutdown Mailtraq, backup + delete database\greylist\*.txt, restart & ask the sender to send. You'd probably see a number of '451' before a known triplet occurred and the message was accepted (this may take hours, or worse, depending on how well the sender is setup to handle a standard greylisting response). The first 451 would confirm that the sender/recipient address whitelisting that you applied is not active on Greylisting.
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