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Delaying/Greylisting

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Delaying/Greylisting

Greylisting involves sending a temporary '451' SMTP error code to the sending server when a message is received. ASSP also creates a 'Triplet' (IP address, Sender & Receiver) and stores this. On the second delivery attempt, if the Embargo Time for the Triplet has passed the message will be accepted and a 'Tuplet' (IP address & Sender) will be created. This Tuplet will not be delayed again for the duration of the Expiry Time.

  • EnableDelaying: Enable Delaying/Greylisting - Enable Greylisting as described at [[1]].

default: 1=activated

  • DelayWL: Whitelisted Greylisting - Enable Greylisting for whitelisted users.
  • DelayNP: NoProcessing Greylisting - Enable Greylisting for noprocessing users.
  • DelaySL: SpamLovers Greylisting - Enable Greylisting for SpamLovers.
  • DelayAddHeader: Add X-Assp-Delayed Header - Add X-Assp-Delayed header to all delayed or whitelisted emails.

default: 1=activated

  • DelayEmbargoTime: Embargo Time - Enter the number of minutes for which delivery, related with new 'Triplet', is refused with a temporary failure.

default: 5 minutes

  • DelayWaitTime: Wait Time - Enter the number of hours to wait for delivery attempts related with recognised 'Triplet'. Delivery is accepted immediately and the 'Tuplet' is saved.

default: 28 hours

  • DelayExpiryTime: Expiry Time - Enter the number of days for which whitelisted 'Tuplet' is considered valid. (Another message from the Tuplet resets this.)

default: 36 days

  • DelayUseNetblocks: Use IP Netblocks - Perform the IP address checks of the sending host based on the /24 subnet rather than the specific IP. This feature may be useful for legitimate mail systems that shuffle messages among SMTP servers between retransmissions.

default: 1=activated

  • DelayNormalizeVERPs: Normalize VERP Addresses - Some mailing lists (such as Ezmlm) try to track bounces to individual mails, rather than just individual recipients, which creates a variation on the VERP method where each email has it's own unique envelope sender. Since the automatic whitelisting (called savelisting to make a difference to the standard whitelisting) that is built into Greylisting depends on the envelope addresses for subsequent emails being the same, the greylisting filter will attempt to normalize the unique sender addresses, when this option is checked.

default: 1=activated

  • DelayMD5: Use MD5 for DelayDB - Message-Digest algorithm 5 is a cryptographic hash function and adds some level of security to the delay database. Must be set to off if you want to list the database with DelayShowDB/DelayShowDBwhite.

default: 1=activated

  • DelayShowDB: Show Delay/Greylisting Database - The directory/file with the delay database file. If you change this in section Filepath you must change it here too.

default: file:delaydb

  • DelayShowDBwhite: Show Delay/Greylisting Save Database - The directory/file with the save delay database file. If you change this in section Filepath you must change it here too.

default: file:delaydb.white

  • DelayExpireOnSpam: Expire Spamming Safelisted Tuplets - If a safelisted 'Tuplet' is ever associated with spam, viri, failed rbl, spf etc, it is deleted from the safelist. This renews the temporary embargo for subsequent mail involving the tuplet.

default: 1=activated

  • CleanDelayDBInterval: Clean Up Delaying Database - Delete outdated entries from triplets and safelisted tuplets databases every this many seconds.

Note: the current timeout must expire before the new setting is loaded, or you can restart.

default: 10800

  • noDelay: Don't Delay these IPs - Enter IP addresses that you don't want to be delayed, separated by pipes (|). There are misbehaving MTAs that will not be able to get a legitimate email through a Greylisting server because they do not try again later. An INCOMPLETE list of such mailers is available at [[2]]. When using this list remember to add trailing dots in IP addresses which specify subnets (eg. 192.168 -> 192.168. ). For example: 145.145.145.145|145.146.

default: file:files/nodelay.txt

  • DelayError: Reply Code to Refuse Delayed Messages - SMTP reply code to refuse delayed messages.

default: 451 4.7.1 Please try again later


ASSP 1.5.x configuration settings

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