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Deferred: 421 Too many concurrent SMTP connections;

PostPosted: Thu Sep 29, 2011 6:02 pm
by gourmet
Subject says it all. That's what SG is replying to SMTP sessions.

After thinking a while I just made this SMTP status check service.

If you find out that email isn't being forwarded normally through SG you can check this url to see SMTP servers status.

http://s.sami-lehtinen.net/c/sc?sg

Re: Deferred: 421 Too many concurrent SMTP connections;

PostPosted: Tue Mar 10, 2020 8:15 pm
by lwc
The aforementioned URL is dead, any chance you'll bring it back to life?

In any case, lately my hosting can no longer write me any messages!
They told me they simply get "Too many concurrent SMTP connections from this IP address; please try again later."
Their IP is 198.61.254.17 and they welcome you to white list if that's the only way.

Below is their log, what could be done? Thanks in advance!

Code: Select all
"delivery-status": {
"mx-host": "gourmet7.spamgourmet.com",
"code": 421,
"description": "",
"session-seconds": 2.9281630516052246,
"retry-seconds": 14400,
"attempt-no": 7,
"message": "Too many concurrent SMTP connections from this IP address; please try again later."
},
"recipient-domain": "neverbox.com",
"event": "failed",
"campaigns": [],
"reason": "generic",
"user-variables": {},
"flags": {
"is-routed": false,
"is-authenticated": true,
"is-system-test": false,
"is-test-mode": false
},
"log-level": "warn",
"timestamp": 1583648629.919381,
"envelope": {
"transport": "smtp",
"sender": "no-reply@fastcomet.com",
"sending-ip": "198.61.254.17",
"targets": "[censored]@neverbox.com"
},
"message": {
"headers": {
"to": "Name <[censored]@neverbox.com>",
"message-id": "c62aa3c5dc911ec03cd2d1ca651a0c09@my.fastcomet.com",
"from": "FastComet General Support <no-reply@fastcomet.com>",
"subject": "[Ticket ID: 256612] [censored]"
},
"attachments": [],
"size": 2769
},
"recipient": "[censored]@neverbox.com",

Re: Deferred: 421 Too many concurrent SMTP connections;

PostPosted: Wed Mar 11, 2020 5:33 am
by gourmet
The server mentioned earlier is currently running in environment where connectivity is really limited on purpose. As example no SMTP connections are allowed.

But there are many other similar or even lot better and versatile tools and SMTP testing services, like the MXtoolbox which is actually quite handy in many situations.

But based on the error message from this IP address, it would indicate it's IP address specific error, and not a global error.

Re: Deferred: 421 Too many concurrent SMTP connections;

PostPosted: Sat Jun 20, 2020 11:21 pm
by isbbs.thebluecat
Hi Lwc and Gourmet,

Please, also see related issue https://bbs.spamgourmet.com/viewtopic.php?f=4&t=1819&sid=3e75f041ff053e35d21a93668dcb6c4c

We are also still waiting for a SpamGourmet Admin to give us some support. :)

Best regards,

A really happy customer of SpamGourmet

Re: Deferred: 421 Too many concurrent SMTP connections;

PostPosted: Wed Jul 15, 2020 6:36 pm
by score
I currently have this issue specifically with Patreon's login service (though not their customer support). I don't know if it affects other mail providers.

Attached is part of the exchange with their support team:

Our support emails send via Zendesk, which is different from our Patreon.com emails which send from specific emails and IP addresses. I've found that private domain email service providers sometimes don't play well with our email notifications.

I looked into our email sending logs, and it looks like recently our emails are failing to reach your inbox. When we attempt to deliver your emails, we receive this response: Too many concurrent SMTP connections from this IP address; please try again later.

It's possible that your email provider is marking Patreon emails as spam, or blocking them from hitting your inbox. Whitelisting Patreon's email will allow all emails to be successfully delivered to your inbox.

When requesting to whitelist Patreon's emails, it's good to know that we primarily send emails through bingo@patreon.com and no-reply@patreon.com. The IP addresses our emails come from are:


159.135.225.154

159.135.225.155

159.135.225.156

69.72.32.187

166.78.71.13

166.78.71.14