Start Date End Date I consent voluntarily to be a participant in this study and
understand that I can refuse to answer questions and
I can withdraw from the study at any time, without having to give a reason.
I understand that information I provide will be
used for scientific reports and publications.
What is the name of your email server software?
Or, what is the name of your MTA?
Are you using any framework, setup tool,
or how to for your mail server?
How many email accounts do exist
under your operated infrastructure?
How many emails does your system
receive on average per day?
Do you frequently update your MTA or
associated plugins and mail filters?
By update, we mean following the releases for the associated
software and installing them regularly.
If yes, approximately when did you last update
your MTA or any of the plugins and mail filters?
What security email protocols do you use? Does your email server validate the sender’s SPF record when it receives an email? What is the name of your SPF milter, mail filter, or plugin? In other words, which plugin or third-party library is doing the SPF validation when an email comes to your server? If your MTA natively supports SPF validation, please mark “MTA Native”. Did you set up the SPF milter yourself? When does your SPF milter perform the SPF resolution of the sender domain? Did you change any of the default values in your SPF milter? (Like changing the default DNS timeout of SPF validation) Did you change any of the following default values in your SPF milter? If yes, please indicate how did you change them. Otherwise, please select the "leave as-is" option. FYI, the RFC recommendation for total DNS lookup and void lookup limits is 10, and 2 respectively.
Response Response Response Other (please specify) Response Other (please specify) Response Other (please specify) Response Other (please specify) Response Date / Time SPF DKIM DMARC BIMI MTA-STS DANE STARTTLS ARC Other (please specify) Response SpamAssassin postfix-policyd-spf iRedAPD libspf/libspf2 spfmilter MTA Native RSpamd Don't Know Other (please specify) Response Response Response Number of permitted DNS lookups per SPF check before an SPF permanent error is raised Number of void DNS lookups per SPF check before an SPF permanent error is raised DNS timeout per SPF check before an SPF permanent error is raised
2022-12-11 17:57:062022-12-11 17:58:01YesYes
2022-12-11 12:19:102022-12-11 12:19:22YesYes
2022-12-07 17:37:162022-12-07 17:39:44YesYesPostfix> 500> 1000Often01/10/2022SPFSTARTTLSNo
2022-12-07 09:50:182022-12-07 09:54:21YesYesExim> 500> 1000Always21/07/2022SPFDKIMSTARTTLSYesSpamAssassinMTA NativeYesAfter the RCPT TO commandNo
2022-12-05 08:47:152022-12-05 08:50:26YesYes
2022-12-03 14:25:552022-12-03 14:28:38YesYesSPFDKIMDMARCMTA-STSDANEYesDon't Know
2022-11-30 22:29:362022-11-30 22:41:50YesYesSendmailOther (please specify)24 years of experience as a postmasterOther (please specify)A handful of accounts with hundreds of email addresses> 1000OftenSPFDKIMDMARCMTA-STSDANESTARTTLSYeslibspf/libspf2 spfmilterYesAfter the MAIL FROM commandYesLeave as-isLeave as-isLeave as-is
2022-11-30 05:01:592022-11-30 05:06:12YesYesOther (please specify)Exchange, Postfix, AxigenOther (please specify)VimbAdmin, Exchange ECP, AxigenOther (please specify)9000> 1000RarelySPFDKIMDMARCYesSpamAssassinMTA NativeNo
2022-11-29 10:03:362022-11-29 10:12:04YesYesOther (please specify)Google WorkSuite aka "gmail"Other (please specify)Google hosted10 ~ 50> 1000NeverSPFDKIMDMARCBIMIMTA-STSDANESTARTTLSARCYesGoogle's own inhouse solutionNo
2022-11-29 08:33:532022-11-29 08:34:24YesYes
2022-11-28 14:44:532022-11-28 14:50:01YesYes
2022-11-27 18:02:152022-11-27 18:05:33YesYesPostfixMailcow<10< 10Always26/10/2022SPFDKIMDMARCMTA-STSSTARTTLSARCYesRSpamdYesAfter the DATA commandNo
2022-11-25 22:08:272022-11-25 22:12:06YesYesOther (please specify)Custom Java appOther (please specify)Other> 500> 1000OftenSPFDKIMDMARCSTARTTLSYesMTA NativeYesDon’t knowYesLeave as-isLeave as-isLeave as-is
2022-11-25 06:42:522022-11-25 06:49:09YesYes
2022-11-25 04:44:282022-11-25 04:44:57YesYes
2022-11-24 09:16:522022-11-24 09:20:47YesYesPostfixOther (please specify)modoboa10 ~ 5010 ~ 100Often01/10/2022SPFDKIMDMARCBIMIMTA-STSSTARTTLSYesSpamAssassinNo
2022-11-24 07:21:242022-11-24 07:23:01YesYesExchange100 ~ 500> 1000AlwaysSPFDKIMSTARTTLSYesSpamAssassinpostfix-policyd-spfNo
2022-11-23 12:53:032022-11-23 12:54:35YesYes
2022-11-23 12:34:192022-11-23 12:53:20YesYesPostfixOther (please specify)Ispconfig100 ~ 500> 1000Often20/10/2022SPFDKIMDMARCSTARTTLSYesRSpamdYesAfter the MAIL FROM commandNo
2022-11-23 11:36:382022-11-23 11:45:29YesYesSendmail> 500> 1000RarelySPFDANESTARTTLSYesSpamAssassinNo
2022-11-23 08:23:342022-11-23 08:24:54YesYes
2022-11-23 07:50:162022-11-23 07:50:29YesYes
2022-11-23 06:54:412022-11-23 06:57:27YesYesHarakaOther (please specify)ProprietaryOther (please specify)~500000Other (please specify)~10000000Often23/11/2022SPFDKIMDMARCBIMIMTA-STSDANESTARTTLSARCYesRSpamdYesAfter the MAIL FROM commandYesLeave as-isLeave as-isLeave as-is
2022-11-23 06:33:322022-11-23 06:33:42YesYes
2022-11-23 06:03:382022-11-23 06:09:18YesYesPostfixOther (please specify)No<1010 ~ 100SometimesSPFDKIMSTARTTLSYesmtpolicydYesAfter the RCPT TO commandNo
2022-11-23 05:20:402022-11-23 05:22:41YesYesEximOther (please specify)Sophos UTM100 ~ 500
2022-11-23 04:51:382022-11-23 04:55:10YesYesPostfixOther (please specify)No framework> 500> 1000Sometimes01/01/2020SPFDANESTARTTLSYesSpamAssassinpostfix-policyd-spfMTA NativeYesAfter the DATA commandYesLeave as-isLeave as-isLeave as-is
2022-11-23 04:26:462022-11-23 04:31:39YesYesEximOther (please specify)Puppet> 500> 1000Always22/11/2022SPFDKIMDMARCSTARTTLSYesSpamAssassiniRedAPDlibspf/libspf2 spfmilterYesAfter the RCPT TO commandYesLeave as-isLeave as-isIncrease
2022-11-23 02:13:322022-11-23 02:16:10YesYesPostfixOther (please specify)Homemade10 ~ 100Always22/11/2022SPFDKIMDMARCSTARTTLSYespostfix-policyd-spfYesAfter the RCPT TO commandNo
2022-11-22 19:37:462022-11-22 19:39:18YesYesPostfixOther (please specify)No> 500> 1000Sometimes01/10/2022SPFDKIMDMARCSTARTTLSYesSpamAssassinlibspf/libspf2 spfmilterNo
2022-11-22 18:57:462022-11-22 19:22:28YesYesPostfix<10101 ~ 1000OftenSPFDKIMDMARCMTA-STSDANESTARTTLSYespostfix-policyd-spf-perlYesAfter the RCPT TO commandNo
2022-11-22 05:15:112022-11-22 17:14:23YesYesExim50 ~ 100> 1000Often21/11/2022SPFDKIMDMARCMTA-STSDANESTARTTLSYesSpamAssassinAfter the DATA commandNo
2022-11-22 17:06:222022-11-22 17:11:52YesYesPostfixOther (please specify)supplied documentation> 500> 1000Always30/09/2022SPFDKIMSTARTTLSYesSpamAssassinamavisd-newYesAfter the full content of the email is receivedNo
2022-11-22 15:30:552022-11-22 15:31:02YesYes
2022-11-22 15:16:422022-11-22 15:16:54YesYes
2022-11-22 14:11:032022-11-22 14:12:30YesYes
2022-11-22 13:31:412022-11-22 13:36:43YesYesPostfixMail-in-a-Box<1010 ~ 100Always01/11/2022SPFDKIMDMARCYesDon't KnowNo
2022-11-22 13:27:372022-11-22 13:27:49YesYes
2022-11-22 13:20:402022-11-22 13:27:25YesYesSendmailOther (please specify)No> 500> 1000Often22/11/2022SPFDKIMDMARCDANESTARTTLSARCYesSpamAssassinpostfix-policyd-spflibspf/libspf2 spfmilterYesAfter the MAIL FROM commandNo
2022-11-22 12:48:372022-11-22 12:55:57YesYesOther (please specify)custom wroteOther (please specify)none> 500101 ~ 1000Often01/10/2022SPFDKIMDMARCNo
2022-11-22 12:29:502022-11-22 12:33:09YesYesOther (please specify)OpenSMTPd50 ~ 100101 ~ 1000Always14/11/2022SPFDKIMDMARCSTARTTLSYesRSpamdYesAfter the HELO/EHLO commandNo
2022-11-22 11:46:162022-11-22 11:49:50YesYesPostfix<10< 10Sometimes02/11/2022SPFDMARCSTARTTLSYesSpamAssassinNo
2022-11-22 11:34:252022-11-22 11:34:47YesYes
2022-11-22 11:25:342022-11-22 11:27:52YesYesPostfixOther (please specify)No> 500> 1000Sometimes22/11/2022SPFDKIMDMARCMTA-STSSTARTTLSNo
2022-11-22 11:27:132022-11-22 11:27:22YesYes
2022-11-22 11:18:042022-11-22 11:25:18YesYesPostfixOther (please specify)ispconfig "control panel" but bulk of config is legacy from pre-ispconfig stand-alone mail serving> 500> 1000Often01/11/2022SPFDKIMDMARCSTARTTLSYesRSpamdNo
2022-11-22 11:18:302022-11-22 11:21:45YesYesPostfix100 ~ 500> 1000AlwaysSPFDKIMDMARCDANESTARTTLSYesSpamAssassinpostfix-policyd-spfYesAfter the HELO/EHLO commandNo
2022-11-22 11:18:372022-11-22 11:20:33YesYesExchangeOther (please specify)none> 500> 1000Always16/11/2022SPFDKIMDMARCSTARTTLSYesMTA NativeNo
2022-11-22 10:31:362022-11-22 10:38:43YesYesSendmailPlesk100 ~ 500101 ~ 1000AlwaysSPFDKIMSTARTTLSYesMTA NativeYesAfter the DATA commandYesLeave as-isLeave as-isLeave as-is
2022-11-22 09:52:202022-11-22 10:34:54YesYesPostfixOther (please specify)manual configuration<10101 ~ 1000Sometimes01/09/2022SPFDKIMDMARCMTA-STSDANESTARTTLSYespolicyd-spfYesAfter the RCPT TO commandNo
2022-11-22 10:34:202022-11-22 10:34:50YesYes
2022-11-22 10:22:092022-11-22 10:25:39YesYesExim50 ~ 100> 1000Often25/10/2022SPFDKIMDMARCMTA-STSSTARTTLSYesSpamAssassinMTA NativeYesAfter the MAIL FROM commandYesLeave as-isLeave as-isLeave as-is
2022-11-22 10:03:212022-11-22 10:03:36YesYes
2022-11-22 09:59:342022-11-22 09:59:40YesYes
2022-11-22 09:58:542022-11-22 09:59:04YesYes
2022-11-22 09:58:272022-11-22 09:58:35YesYes
2022-11-22 09:50:052022-11-22 09:54:35YesYesOther (please specify)SmarterTools, SmarterMail> 500> 1000Often21/11/2022SPFDKIMDMARCSTARTTLSYesMTA NativeNo
2022-11-22 08:26:312022-11-22 08:26:56YesYes
2022-11-22 04:27:032022-11-22 04:31:37YesYesPostfixOther (please specify)None> 500> 1000Often20/11/2022SPFDKIMDMARCSTARTTLSARCYesRSpamdYesAfter the HELO/EHLO commandYesIncreaseLeave as-isIncrease
2022-11-22 04:26:232022-11-22 04:30:16YesYesPostfixOther (please specify)Puppet + Ansible> 500> 1000Always18/11/2022SPFDKIMDMARCBIMIMTA-STSSTARTTLSYesSpamAssassinpostfix-policyd-spfYesAfter the full content of the email is receivedYesIncreaseLeave as-isIncrease
2022-11-22 03:45:122022-11-22 04:10:31YesYesOther (please specify)Courier-MTAOther (please specify)home-brewed scripts10 ~ 50101 ~ 1000Often08/11/2022SPFDKIMDMARCMTA-STSDANESTARTTLSYesMTA NativeYesAfter the MAIL FROM commandYesLeave as-isLeave as-isLeave as-is
2022-11-22 03:46:512022-11-22 03:58:55YesYesPostfix(ISP) Mail Server Howto> 500> 1000Often16/11/2022SPFDKIMDMARCBIMIMTA-STSDANESTARTTLSARCYespostfix-policyd-spfRSpamdYesAfter the full content of the email is receivedYesDecreaseDecreaseDecrease
2022-11-22 03:37:592022-11-22 03:41:09YesYesPostfixOther (please specify)self-developed solution> 500> 1000Always14/11/2022SPFDKIMSTARTTLSYespostfix-policyd-spfYesDon’t knowNo
2022-11-22 02:08:382022-11-22 02:11:33YesYesExchangeOther (please specify)No> 500> 1000Often15/11/2022SPFDKIMDMARCNo
2022-11-22 01:40:112022-11-22 01:43:58YesYesPostfixMailcow<10101 ~ 1000
2022-11-21 23:35:492022-11-21 23:41:53YesYesEximOther (please specify)saltstack<10101 ~ 1000Often13/07/2021SPFDKIMDMARCMTA-STSSTARTTLSIP + hostname denylist / allowlistNo
2022-11-21 22:09:042022-11-21 22:10:24YesYes
2022-11-21 20:49:122022-11-21 20:51:50YesYesPostfix<10< 10Often01/11/2022SPFDKIMDMARCDANESTARTTLSYesMTA NativeYesDon’t knowNo
2022-11-21 17:51:532022-11-21 18:00:38YesYesOther (please specify)SurgemailOther (please specify)None<1010 ~ 100Sometimes22/11/2021SPFDKIMDMARCSTARTTLSYesMTA NativeYesAfter the full content of the email is receivedNo
2022-11-21 17:28:242022-11-21 17:34:38YesYesEximOther (please specify)None<1010 ~ 100SometimesSPFDKIMDMARCDANESTARTTLSYesMTA NativeYesAfter the MAIL FROM commandYesLeave as-isLeave as-isLeave as-is
2022-11-21 17:28:442022-11-21 17:33:50YesYesPostfix<1010 ~ 100Sometimes01/06/2021SPFDMARCNo
2022-11-21 17:26:062022-11-21 17:30:17YesYesEximOther (please specify)none<1010 ~ 100AlwaysNo
2022-11-21 16:56:302022-11-21 16:57:39YesYes
2022-11-21 16:32:552022-11-21 16:50:28YesYesPostfixOther (please specify)by my own> 500> 1000Always10/11/2022SPFDKIMDMARCMTA-STSDANESTARTTLSARCYesRSpamdYesAfter the full content of the email is receivedYesIncreaseIncreaseIncrease
2022-11-21 15:48:592022-11-21 15:51:49YesYesPostfixOther (please specify)No> 500> 1000Often01/10/2022SPFDKIMDMARCSTARTTLSYespostfix-policyd-spfYesAfter the RCPT TO commandNo
2022-11-21 15:31:322022-11-21 15:39:06YesYesPostfix> 500101 ~ 1000Always21/11/2022SPFSTARTTLSYesRSpamdNo
2022-11-21 15:11:202022-11-21 15:13:16YesYes
2022-11-21 14:27:052022-11-21 15:09:14YesYesPostfix(ISP) Mail Server Howto10 ~ 50101 ~ 1000OftenSPFDKIMSTARTTLSNo
2022-11-21 14:55:402022-11-21 15:05:50YesYesPostfixOther (please specify)It's a gigantic cloud service that uses Postfix internally but a lot of custom software as well.Other (please specify)Tens of millionsOther (please specify)>100MAlways21/11/2022SPFDKIMDMARCMTA-STSDANESTARTTLSARCYeslibspf/libspf2 spfmilterYesAfter the full content of the email is receivedNo
2022-11-21 14:47:022022-11-21 14:51:19YesYesExim10 ~ 5010 ~ 100OftenSPFDKIMYesMTA NativeYesNo
2022-11-21 14:36:452022-11-21 14:44:57YesYesEximOther (please specify)mix of docs & mailing list/IRC asks and various other sources<1010 ~ 100Often01/11/2022SPFDKIMDMARCSTARTTLSYesRSpamdspfquery (perl) directly from eximYesAfter the DATA commandNo
2022-11-21 14:15:292022-11-21 14:30:02YesYesOther (please specify)Hurricane MTAOther (please specify)None> 500> 1000Always15/11/2022SPFDKIMDMARCMTA-STSSTARTTLSYesMTA NativeYesAfter the RCPT TO commandNo
2022-11-21 14:29:382022-11-21 14:29:51YesYes
2022-11-21 14:13:162022-11-21 14:21:38YesYesExim> 500> 1000Often01/07/2022SPFDKIMDMARCSTARTTLSYesRSpamdYesAfter the full content of the email is receivedNo
2022-11-21 14:15:142022-11-21 14:16:03YesYes
2022-11-21 14:11:202022-11-21 14:12:05YesYes
2022-11-21 14:06:182022-11-21 14:07:02YesYes
2022-11-21 11:51:352022-11-21 12:44:00YesYesPostfixMailcow<10101 ~ 1000Often26/10/2022SPFDKIMDMARCDANESTARTTLSYesRSpamdNo
2022-11-21 11:34:182022-11-21 12:31:27YesYesPostfixOther (please specify)none50 ~ 100101 ~ 1000Sometimes01/11/2022SPFDKIMDMARCDANESTARTTLSYesSpamAssassinlibspf/libspf2 spfmilterYesAfter the RCPT TO commandNo
2022-11-21 11:38:452022-11-21 11:48:05YesYesPostfixMailcow10 ~ 5010 ~ 100Always14/11/2022SPFDKIMDMARCSTARTTLSYesRSpamdNo
2022-11-21 11:39:412022-11-21 11:45:07YesYesPostfix<1010 ~ 100Often15/08/2022SPFDKIMDANESTARTTLSYesSpamAssassinDon't KnowYesDon’t knowNo
2022-11-21 11:42:412022-11-21 11:43:35YesYes
2022-11-21 11:34:592022-11-21 11:40:54YesYesPostfixOther (please specify)None> 500> 1000Often18/11/2022SPFDKIMDMARCDANESTARTTLSYesSpamAssassinpostfix-policyd-spfYesAfter the RCPT TO commandNo
2022-11-21 11:33:562022-11-21 11:39:05YesYesPostfixOther (please specify)postfixadminOther (please specify)5000Other (please specify)100Always21/11/2022SPFDKIMDMARCMTA-STSDANESTARTTLSYesSpamAssassinpostfix-policyd-spfRSpamdYesDon’t knowYesLeave as-isLeave as-isLeave as-is
2022-11-21 11:35:212022-11-21 11:37:26YesYesOther (please specify)Microsoft 365100 ~ 500> 1000SPFDKIMDMARCSTARTTLSYesDon't KnowNo