Send Emails failing: ESMTP server not available (blacklisted by local policy) from Static IP

[#1]

I have several Plusnet email addresses associated with my Plusnet Boradband account.

One of these accounts is setup to send notifications:

1) From my FritzBox router.

2) My IP CCTV cameras also use this address to send notifications of detected movement.

3) Blat32 for other notifications

Unfortunately all these stopped working a while ago and even the main Plusnet email address is no longer able to send emails frorm home either.

Using Thunderbird to send an email from the Plusnet email accounts I get the following message:

"Sending of the message failed.
An error occurred while sending mail: Outgoing server (SMTP) error. The server responded: avasout-peh-004 smtp ESMTP server not available (blacklisted by local policy)."

I have other email accounts using other service providers (AOL etc) - and there are no problems sending messages from these accounts from the same PC using Thunderbird.

Also sending from the same Plusnet email account using browser based webmail is fine.

All tests are from my home address which is connected via Plusnet FTTC which has a static ip.

From other posts here it appears that my static ip address may have been blacklisted?

Is there anyway I can get this lifted?

I only send emails to my self and one other person using this Plusnet email address.

Hopefully someone can advise?

[#2]

Are you using a VPN?

[#3]

Hello,

Thanks for the message.

I do have a VPN configured on my router which was used for a day or two in early January.

I have disabled it for the time being as I plan to use a standalone device for the vpn in future so that I can use split tunelling (not a feature on the router)  - but I haven't got around to it yet.

Looking back at when my camera notifications stopped (ie blocked) it was around 14/12/2023 I think - going back through my emails.

Regards,

[#4]

If there is a VPN involved here, then the SMTP connection would be deemed "off network" and thus (a) the connection MUST be authenticated and (b) there is a risk of the VPN IP address being deemed unsafe.

[#5]

Thanks again

I'm not sure that I understand - there is no VPN. The router only used it for a day or so in January and was disabled.

Has this temporary use triggered the block?

The VPN is not enabled and hasn't been since January.

However, as far as I can tell, the emails started being blocked in December before the VPN was (briefly) used in January.

Do you have any suggestions as to what I should do to get this working again please?

[#6]

Test SMTP authentication

Email programs often report username / password error for issues not actually related to those being wrong, but for other connectivity issues. Such can be very frustrating when you are convinced that they are correct. Testing SMTP authentication through a command line interface can deliver a more precise error message. The following describes how to do this using TELNET.

This is not difficult, but you need the following resources which might be unfamiliar...

1. TELNET - this might need installing as an additional option, for Windows see enabling TELNET.
2. A code64 encoder / decoder such as this.

You can use TELNET to communicate direct with the SMTP server as follows...

Open the code64 encoder in a web browser and leave ready for use in the following steps.

Launch a windows command line window (DOS window) - press windows-key+R - type CMD into the run box - click OK

Enter...

telnet relay.plus.net 587

Press enter. Note if you use one of the other brand email services, use the appropriate SMTP server name for that brand. In response to SMTP server I'm here message, say 'HELLO'...

EHLO relay.plus.net

The SMTP server will then report what it can do after which tell the server you wish to authenticate...

AUTH login

The server should return the following, which is a base64 encoded string that requires your username:

334 VXNlcm5hbWU6

Use the code64 encoder to encode your username and paste it into the telnet window and press enter. For example:

bXl1c2VybmFtZQ==

The server should return the following, which is a base64 encoded string that requires your password:

334 UGFzc3dvcmQ6

Paste the base64 encoded password for the username. For example:

bXlwYXNzd29yZA==

The server will then report success or failure, any failure message should clearly indicate the reason for the failure. If the reason for the failure is not clear, please report back the message.

Close the SMTP / TELNET session by entering

quit

The session should look something similar to the below wherein your input is in bold...

220 avasout03 smtp relay.plus.net
EHLO relay.plus.net
250-avasout03 hello [your IP address], pleased to meet you
250-HELP
250-AUTH LOGIN PLAIN
250-SIZE 104857600
250-PIPELINING
250-8BITMIME
250-STARTTLS
250 OK
AUTH LOGIN
334 VXNlcm5hbWU6
bXl1c2VybmFtZQ==
334 UGFzc3dvcmQ6
bXlwYXNzd29yZA==
235 ... authentication succeeded
quit
221 avasout03 smtp closing connection
Connection to host lost.

Here are some examples of failure responses...

535 ...authentication rejected [as username / password is wrong]
535 ...authentication rejected as source IP has a poor reputation
535 Too many SMTP auth failures. Please try again later.

[#7]

Hello,

I already have telnet enabled but I am not sure I can get any further than this?:

C:\Users\???>telnet relay.plus.net 587

554 avasout-ptp-001 smtp ESMTP server not available (blacklisted by local policy)

Connection to host lost.

C:\Users\???>

Am I missing something here?

[#8]

That implies that your IP address has been black balled ... which seems odd.

I would suggest try forcing a change of IP address - this is clunky and inconvenient, but might be your only way forward.  These days dynamic IP addresses are sticky and are difficult to force a change.

1. Find out what your EXTERNAL IP address is currently (search whatsmyipaddress)
2. Do a WHOIS lookup on the the IP address and confirm that it belongs to Plusnet (or BT)
3. Power off the router for at least 90 minutes
4. Power the router on again
5. Find out what your EXTERNAL IP address is now (search whatsmyipaddress) hopefully it will be different
6. Repeat the test

[#9]

Thanks again.

I do know that I have a static IP address - I was able to get this some years ago when Plusnet offered them.

Would powering off the router make any difference in this case?

I tried explaining this to the Plusnet Support staff a couple of days ago but I don't think they understood.

[#10]

Oh that is disconcerting!!

No, the above is not going to help.

I suggest that you look at blacklists - put the IP address into the various tools provided here - Email Blacklist Check - IP Blacklist Check - See if your server is blacklisted (mxtoolbox.com)

If the IP address reports as being blocked by any of the black listers, then report that back here, use whatever options you can to request their removal.

Thereafter, call support and explain "Plusnet's SMTP server is blocking my PLUSNET STATIC IP address - can you please raise a ticket requesting second line investigation".

[#11]

Thanks for the further advice

It seems that my IP address is being blacklisted by Spamhaus ZEN

I am on their Policy Blocklist (PBL)

Their explanation is:

What is the Policy Blocklist (PBL)?

The Policy Blocklist (PBL) lists IP space that should not be sending email directly to the Internet/direct-to-mx: often these are IP ranges assigned by ISPs to broadband or dial-up customers, but the PBL does include other types of IP space.

Any IP space that should not be sending email directly to the Internet should be listed in PBL.

PBL listings do not prevent the sending of email unless the user’s email program is not authenticating correctly when connecting to their ISP or company’s mail server. Possible causes for this happening suddenly: changing settings or email software, forgetting to turn “SMTP Authentication” on, or switching “SMTP Authentication” off.

They go further:

The inclusion of your IP address on the Policy Blocklist (PBL) is standard for the vast majority of internet users and is not the result of your actions. Here are some key PBL facts for your understanding:

• Being on this list does not mean you won’t be able to send emails.
• You do not need to request removal from PBL.
• This listing is controlled by your Internet Service Provider (ISP), not Spamhaus.
• Your ISP lists ranges of IP addresses that shouldn’t be sending email directly to the internet.
• Typically, IPs of broadband or dial-up customers will be included in this list.
• This is part of Internet best practices enacted to protect all users.

So with the line highlighted above it would seem that only Plusnet can resolve this?

[#12]

To be clear, you are not running your own MX server - are you?

Note: PBL listings do not prevent the sending of email unless the user’s email program is not authenticating correctly when connecting to their ISP or company’s mail server.

This suggests that the connection is not authenticating ... and needs assistance from second line support.

For the avoidance of doubt, you are using Plusnet as your ISP here and is this email associated with your current Plusnet service or is it a legacy email service, connected with a previous Plusnet account?

[#13]

It might sound a little dumb - but I am not sure.

I use a command line SMTP utility called BLAT.EXE which can be used to send emails.

I had a batch file setup use this utility to email me and one other person three times a day (with attachments) using SMTP.

This had been setup and used without any issue for years - since 2016 as far as I can tell.

I have had my Static IP for longer than that I think.

[#14]

---

@Radar59 wrote:

... I can get any further than this?:

C:\Users\???>telnet relay.plus.net 587

554 avasout-ptp-001 smtp ESMTP server not available (blacklisted by local policy)
Connection to host lost.

Revisiting the above, the response should be...

220 avasout-peh-003 smtp relay.plus.net

After which you get on typing the next line in the test script.

What is odd in your report is ESMTP which implies an encrypted connection ... which I do not understand how telnet can facilitate.

I would first confirm that from your computer you can make a simple direct connection to the SMTP server, either using the diagnostic I supplied above or a straightforward email client.  Only after that would I turn to investigating the SMTP reporting tools further.

There was elsewhere around here a two reports of the same third party back up tool which stopped sending emails in the manner you allude to here.  Their 2022 product worked fine, the 2023 and 2024 versions did not.  The users in those cases took the issue to the product vendors ... who eventually provided a fix to their email module.

[#15]

Thanks again!

To eliminate my windows 10 PC from this problem I used telnet from my Raspberry Pi

pi@Pi-Hole:~ $ telnet relay.plus.net 587
Trying 212.159.9.107...
Connected to relay.plus.net.
Escape character is '^]'.
554 avasout-ptp-004 smtp ESMTP server not available (blacklisted by local policy)
Connection closed by foreign host.

The same error is returned.

On the same Windows PC I use an email backup utility called Zebnet. the application can send notifications when the backup has finished etc. This also fails with my plusnet email address

I have a REolink IP CCTV camera wihch uses the same sending email address to notify motion detection. This also no longer works.

Neither does the notifications that used to be sent from my Fritz router.

I am not sure how either the Reolink cameras or the Fritz router handle sending of the notification emails via smtp but they had also been working for years now.