421 Server SMTP server Error

[waddelljb]

I have tried repeatedly and spent 2 hours going nowhere with Virgin Media customer support on the phone.

I have changed the password for the ntlworld email account and I am  still getting the dreaded: 

"Send test email message: The server responded: 421 csmtp6.tb.ukmail.iss."

I am using POP 3 on outlook.

I have deleted the ntlworld.com email account profile in outlook and recreated the profile using the standard settings https://www.virginmedia.com/help/virgin-media-mail-update-settings-in-microsoft-outlook 

I can now login for incoming mail, but fail with the 421 Server error for sending.

All community posts suggest a private message fix.  Please can someone technical  unblock the IP address as I understand it's probable that it is a blacklisting of some sort for IP address or email.  Any assistance greatly appreciated. Thanks

[coenoby]

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@waddelljb wrote:

The server responded: 421 csmtp6.tb.ukmail.iss."

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In fact, SMTP error code 421 is just a generic response that  says there is a temporary problem with the service.

It's the next part of the error message that gives the exact reason so you really need to post that here. Without that it's impossible to know what's going on.

I suspect it's the "Too many bad emails have been sent" error that you are seeing but I have learnt the hard way that I should never assume 😉

Post the full error message but don't post your or the receiver's  email address.

Coenoby

[waddelljb]

Thanks so much for replying. 
The only message I am getting for send email in setting up the new Outlook profile is:

"Send test email message: The server responded: 421 csmtp6.tb.ukmail.iss."

Does that help?

Regards

James

[coenoby · Accepted solution]

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@waddelljb wrote:

"Send test email message: The server responded: 421 csmtp6.tb.ukmail.iss."     Does that help?

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Not really I'm sorry to say.
As I said in my first post 421 is a generic error that basically says "computer says no" and by itself it does not offer any clue as to why.

You referred in your original post to "All community posts suggest a private message fix. Please can someone technical unblock the IP address as I understand"

However I think you'll find that those posts were in answer to specific errors such as:

"421 csmtp1.tb.ukmail.iss.as9143.net cmsmtp Virgin Media has blocked your connecting IP xx.x.xx.xxx Too many bad emails have been sent

or  "smtp; 421 4.2.0 MXIN618Temporary SMC Policy Violation detected"

You say that you are not seeing either of those phrases I have emboldened so the problem could well be down to something else rather than a blacklisted IP address.

The first thing I would check is that you are using the correct / latest VM email settings in Outlook:

Make sure the Outgoing server (SMTP) settings in Outlook are:

• Outgoing mail server (SMTP): smtp.virginmedia.com (even if your email address ends in ntlworld.com, blueyonder.co.uk  or virgin.net)
  
• User Name: Your full email address e.g. Richard.Branson@ntlworld.com
• Port: 465
• In "Use the following type of encrypted connection"that you have selected: SSL / TLS

The other thing that would be worth checking before you go any further is that you can access your email account from the VM website using this link https://mail2.virginmedia.com/  If that generates an error then Outlook will not be able to access the server either.

Post back with how you get on. 😉

Coenoby

[waddelljb]

The plot thickens...

Using the Virginmedia broadband connection:

I had already used the settings you recommended.
I have no other error message information.

However, I tried to create the same ntlworld account in Outlook on another computer (laptop)  and bingo I am in and receiving and sending emails.  The laptop computer was using a sky broadband connection.

So this suggests perhaps:

1 Outlook is corrupt in someway.

I am tempted to do a brute force approach and uninstall Outlook and reinstall.

I have already deleted outlook.ost No change.

2 There is an IP address issue with the Virginmedia  broadband connection.

I will take my laptop to the Virginmedia location and ethernet cable it in and see what happens.

Any other thoughts?

[coenoby]

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@waddelljb wrote:

Any other thoughts?

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I have many.many thoughts 🙂

However, two of them are relevant here.

My first thought:

You need to access your email account from the VM website using this link https://mail2.virginmedia.com/   and see if you can successfully send an email from there.

My second thought

You need to find out why VM is not allowing your copy of Outlook to sync with your email account and that means we need to discover the error code that the VM server is reporting back to Outlook. Sadly Outlook like most email apps does not report back the full error details that it gets from the server.

What we are looking for is a code in the format VMnnn

The easiest way to get that is to use the curl command which comes as a standard part of Windows 10.

Here is a step by step guide:

1) Copy the following line of command text and then paste it into a MS Word document (or which ever text editor you prefer)  so that you can edit it.

curl -v smtps://smtp.virginmedia.com -u Username:Password 2>&1 | findstr "235 VM"

2) Once you have pasted it into Word, replace Username with your full Virgin Media email address,  and   Password  with the new password you reset it to. So that part should now say something like     richardbranson@ntlworld.com:sdfxyz1234        It is important to keep the colon  :  and the space before and after that piece of text exactly as per the original line of text in step 1.

3) Now type cmd into the Windows 10 search bar, press Enter and then Open the Command Prompt app.

4) Copy the full line of text that you just amended in step 2 from the Word document and paste it where the curser is blinking in the Command Prompt. Then press Enter.

After a second or two you should then see a line which says something like < 535 5.7.8 Authentication Credentials Invalid (VM300)

It is that line, particularly the VMxxx code that we need you to give us please.

Coenoby

[waddelljb]

Thanks again I tried the curl command and it gave no response.

After spending another 6 hours pulling my hair out, I got a computer techy in.

He finally figured out that:

The dynamic IP address on the virgin router is blocked for SMTP to virginmedia.com. The dynamic IP address will change on 22 October 2021 and so the block should fall off. This can be seen by accessing the router. SMTP to another email account, not virginmedia, worked fine through the virginmedia router.

In the meantime he installed a free VPN to workaround the blocked IP address and get the ntlworld account.com to work.  So Outlook SMTP to virginmedia works with VPN, but not without.

He suspected that the hard drive may have been infected with a SPAM virus so he installed a new operating system and mapped  the data drives to the new WINDOWS 10 boot.

On 23 October, we remove the VPN and expect Outlook to work normally as we should have a new dynamic IP address for the router.

I share this as it may help others.

Thanks again for your support.

[jem101]

I can safely say that on October 22nd you will not get a different IP address.

Who told you that you would and why did they think that?

[coenoby]

@waddelljb 

I suggested trying that curl command to see what  error VM were reporting. That could indeed have indicated whether your IP address had been blacklisted due to spambot activity on your home network.

You could look here https://whatismyipaddress.com/ to check your IP address and then enter the address here  https://mxtoolbox.com/blacklists.aspx  to check your IP address against a number of blacklists. You could also check on here https://check.spamhaus.org/  because that is one blacklist VM have used in the past.

I agree with @jem101, I cannot see why your IP address will change on October 22nd.

Also, worth saying that If it is a spambot malware that has caused the IP address to  be blacklisted that could have infected any smart device on your home network not necessarily your Windows 10 machine.

Coenoby

[coenoby]

@waddelljb 

Apologies, in my last post I also meant to say that VM do seem to be using their own blacklist these days so your IP could still be blocked by VM even though it does not appear on the more generally used lists on the links I gave. 

However, that is usually reported in full in the error message. As an example:

"421 csmtp3.tb.ukmail.iss.as9143.net cmsmtp Sorry your IP 86.xx.xx.xxx is active in our local abuse blacklist."

However, you are not seeing that error.

Coenoby