Some links on SMTP tar-pit to lessen SPAM

November 2021
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Posted by jpluimers on 2021/11/03

Some links for my archive; note that pure tar-pits by now are also hampering large email sender services like SendGrid, Mailgun and Amazon SES.

So the below links are for educational and historic purposes only.

Teergrube (Informationstechnik): SMTP Teergruben – Wikipedia
- [WayBack] Lutz Donnerhacke: Teergruben FAQ
Tarpit (networking): SMTP tarpits – Wikipedia
- [WayBack] GitHub – martinh/mxtarpit: Fake SMTP Backup MX Tarpit
- [WayBack] incidents 2003/02: Re: email address probes
[WayBack] Spam Filtering for Mail Exchangers
- [WayBack] Spam Filtering for Mail Exchangers: Techniques
  - [WayBack] SMTP Transaction Delays
  - [WayBack] DNS Checks
  - [WayBack] SMTP checks
  - [WayBack] Greylisting
  - [WayBack] Sender Authorization Schemes
  - [WayBack] Message data checks
  - [WayBack] Blocking Collateral Spam
- [WayBack] Spam Filtering for Mail Exchangers: Credits
Greylisting – Wikipedia
Apache SpamAssassin – Wikipedia
GTUBE (“Generic Test for Unsolicited Bulk Email”) – Wikipedia
- EICAR Anti-Virus Test File – Wikipedia

I assembled these links because out of a sudden, Ring 2FA verification emails could not be delivered any more.

Ring 2FA came mandatory towards the end of February 2020.

Some links on that:

[WayBack] Subdomain Finder scan of ring.com – C99.nl
[WayBack] Ring in the changes: Mandatory two-factor authentication, login alerts, targeted ads opt-out after punters voice privacy gripes • The Register
[WayBack] Ring doorbell makes two-factor verification mandatory – BBC News
[WayBack] Enhancing Security with Two-Step Verification – Ring Help
[WayBack] Two-Step Verification – Ring Help
[WayBack] GitHub – dgreif/ring: Unofficial API for Ring Doorbells, Cameras, Alarm System, and Smart Lighting
- [WayBack] Two Step Verification now required for every login…? · Issue #256 · dgreif/ring · GitHub
  
  The purpose of Two-Step Verification (2SV) is to protect you from bad actors logging into your Ring account, even if those bad actors have the proper login credentials. This feature will be enabled by default for all users and, unlike 2FA, there is no user option to opt out.
- [WayBack] Two Factor Auth · dgreif/ring Wiki · GitHub

Sendmail timeouts:

–jeroen

	2020-03-31T10:08:34.402372+02:00 snap sendmail[29592]: NOQUEUE: connect from o6.sg.account.ring.com [198.21.6.126]
	2020-03-31T10:10:05.550572+02:00 snap sendmail[30013]: NOQUEUE: connect from o6.sg.account.ring.com [198.21.6.126]
	2020-03-31T10:10:34.521709+02:00 snap sendmail[29592]: 02V88YAS029592: o6.sg.account.ring.com [198.21.6.126] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:12:05.673585+02:00 snap sendmail[30013]: 02V8A5RQ030013: o6.sg.account.ring.com [198.21.6.126] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:12:10.479557+02:00 snap sendmail[30057]: NOQUEUE: connect from o6.sg.account.ring.com [198.21.6.126]
	2020-03-31T10:13:31.911468+02:00 snap sendmail[30544]: NOQUEUE: connect from o7.sg.account.ring.com [149.72.233.225]
	2020-03-31T10:14:10.599326+02:00 snap sendmail[30057]: 02V8CAu4030057: o6.sg.account.ring.com [198.21.6.126] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:14:40.481324+02:00 snap sendmail[30547]: NOQUEUE: connect from o6.sg.account.ring.com [198.21.6.126]
	2020-03-31T10:15:05.916150+02:00 snap sendmail[30549]: NOQUEUE: connect from o7.sg.account.ring.com [149.72.233.225]
	2020-03-31T10:15:32.033826+02:00 snap sendmail[30544]: 02V8DVFZ030544: o7.sg.account.ring.com [149.72.233.225] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:16:40.604351+02:00 snap sendmail[30547]: 02V8EeRr030547: o6.sg.account.ring.com [198.21.6.126] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:17:06.033592+02:00 snap sendmail[30549]: 02V8F5ZY030549: o7.sg.account.ring.com [149.72.233.225] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:17:10.891192+02:00 snap sendmail[30595]: NOQUEUE: connect from o6.sg.account.ring.com [198.21.6.126]
	2020-03-31T10:17:40.447080+02:00 snap sendmail[30603]: NOQUEUE: connect from o6.sg.account.ring.com [198.21.6.126]
	2020-03-31T10:19:11.012476+02:00 snap sendmail[30595]: 02V8HAXM030595: o6.sg.account.ring.com [198.21.6.126] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:19:40.569264+02:00 snap sendmail[30603]: 02V8Heh3030603: o6.sg.account.ring.com [198.21.6.126] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:19:40.987599+02:00 snap sendmail[31105]: NOQUEUE: connect from o6.sg.account.ring.com [198.21.6.126]
	2020-03-31T10:21:08.069249+02:00 snap sendmail[31108]: NOQUEUE: connect from o6.sg.account.ring.com [198.21.6.126]
	2020-03-31T10:21:41.113096+02:00 snap sendmail[31105]: 02V8JeiK031105: o6.sg.account.ring.com [198.21.6.126] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:22:40.174575+02:00 snap sendmail[31136]: NOQUEUE: connect from o6.sg.account.ring.com [198.21.6.126]
	2020-03-31T10:22:40.426572+02:00 snap sendmail[31137]: NOQUEUE: connect from o6.sg.account.ring.com [198.21.6.126]
	2020-03-31T10:22:40.919578+02:00 snap sendmail[31138]: NOQUEUE: connect from o6.sg.account.ring.com [198.21.6.126]
	2020-03-31T10:23:08.186602+02:00 snap sendmail[31108]: 02V8L8o4031108: o6.sg.account.ring.com [198.21.6.126] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:24:40.295996+02:00 snap sendmail[31136]: 02V8Me0L031136: o6.sg.account.ring.com [198.21.6.126] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:24:40.553121+02:00 snap sendmail[31137]: 02V8MeoI031137: o6.sg.account.ring.com [198.21.6.126] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:24:41.042658+02:00 snap sendmail[31138]: 02V8MeN5031138: o6.sg.account.ring.com [198.21.6.126] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:24:45.154333+02:00 snap sendmail[31622]: NOQUEUE: connect from o6.sg.account.ring.com [198.21.6.126]
	2020-03-31T10:26:45.275350+02:00 snap sendmail[31622]: 02V8OjB4031622: o6.sg.account.ring.com [198.21.6.126] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:27:20.172571+02:00 snap sendmail[31643]: NOQUEUE: connect from o7.sg.account.ring.com [149.72.233.225]
	2020-03-31T10:27:40.905307+02:00 snap sendmail[31646]: NOQUEUE: connect from o6.sg.account.ring.com [198.21.6.126]
	2020-03-31T10:29:20.297002+02:00 snap sendmail[31643]: 02V8RKtX031643: o7.sg.account.ring.com [149.72.233.225] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:29:41.026274+02:00 snap sendmail[31646]: 02V8Rea4031646: o6.sg.account.ring.com [198.21.6.126] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:30:25.152770+02:00 snap sendmail[32193]: NOQUEUE: connect from o7.sg.account.ring.com [149.72.233.225]
	2020-03-31T10:32:00.519601+02:00 snap sendmail[32200]: NOQUEUE: connect from o7.sg.account.ring.com [149.72.233.225]
	2020-03-31T10:32:25.265366+02:00 snap sendmail[32193]: 02V8UPaR032193: o7.sg.account.ring.com [149.72.233.225] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:34:00.646026+02:00 snap sendmail[32200]: 02V8W0ev032200: o7.sg.account.ring.com [149.72.233.225] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:35:30.172349+02:00 snap sendmail[32716]: NOQUEUE: connect from o6.sg.account.ring.com [198.21.6.126]
	2020-03-31T10:37:00.906561+02:00 snap sendmail[32741]: NOQUEUE: connect from o7.sg.account.ring.com [149.72.233.225]
	2020-03-31T10:37:30.286290+02:00 snap sendmail[32716]: 02V8ZUQt032716: o6.sg.account.ring.com [198.21.6.126] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:39:01.029903+02:00 snap sendmail[32741]: 02V8b084032741: o7.sg.account.ring.com [149.72.233.225] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:44:55.825852+02:00 snap sendmail[1305]: NOQUEUE: connect from o7.sg.account.ring.com [149.72.233.225]
	2020-03-31T10:46:55.945400+02:00 snap sendmail[1305]: 02V8itAF001305: o7.sg.account.ring.com [149.72.233.225] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:48:00.506257+02:00 snap sendmail[1337]: NOQUEUE: connect from o7.sg.account.ring.com [149.72.233.225]
	2020-03-31T10:50:00.627510+02:00 snap sendmail[1337]: 02V8m0vd001337: o7.sg.account.ring.com [149.72.233.225] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T10:53:01.158286+02:00 snap sendmail[1886]: NOQUEUE: connect from o6.sg.account.ring.com [198.21.6.126]
	2020-03-31T10:55:01.291552+02:00 snap sendmail[1886]: 02V8r1Eg001886: o6.sg.account.ring.com [198.21.6.126] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T11:01:02.131569+02:00 snap sendmail[3020]: NOQUEUE: connect from o7.sg.account.ring.com [149.72.233.225]
	2020-03-31T11:03:02.245406+02:00 snap sendmail[3020]: 02V912kf003020: o7.sg.account.ring.com [149.72.233.225] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T11:19:00.525396+02:00 snap sendmail[5045]: NOQUEUE: connect from o7.sg.account.ring.com [149.72.233.225]
	2020-03-31T11:21:00.650971+02:00 snap sendmail[5045]: 02V9J0Tm005045: o7.sg.account.ring.com [149.72.233.225] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
	2020-03-31T11:24:01.416265+02:00 snap sendmail[5594]: NOQUEUE: connect from o6.sg.account.ring.com [198.21.6.126]
	2020-03-31T11:26:01.530327+02:00 snap sendmail[5594]: 02V9O1bx005594: o6.sg.account.ring.com [198.21.6.126] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA

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ring.smtp.log

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This entry was posted on 2021/11/03 at 06:00 and is filed under *nix, Communications Development, Development, HIS Host Integration Services, Internet protocol suite, Power User, SMTP. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Some links on SMTP tar-pit to lessen SPAM

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The Wiert Corner – irregular stream of stuff

Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Some links on SMTP tar-pit to lessen SPAM

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