Cannot send email: smtp ESMTP server not available (blacklisted by local policy)

[#1]

Unfortunately, my senderscore is still "0:POOR"

I'm not sure how/if/when that would get updated?

[#2]

I'm not sure when that will updated either ?

Did you look at the 'more info' when checking your IP on the spamhaus site ?

The HELO values shown seem strange , apart from the one showing your correct <account>.plus.com ?

[#3]

Yes, those HELO values do look strange... I don't know where those others are coming from 😬

[#4]

As Spamhaus suggest checking , is there ANY possibility that one of your devices has malware ?

[#5]

I shall do another deep scan... starting with my teenagers devices 🙄

Can I set any further firewall rules on my Plusnet Two Hub router which may help block malicious activity?

[#6]

Not that I'm aware of but I dont actually use a Hub 2

[#7]

Update:
I'm still unable to send email using my static IP—this has been ongoing for over a week.

• Spamhaus has delisted my IP.

• My SenderScore has improved slightly but remains poor (13).

• I've updated SPF and other DNS records within my control (DKIM doesn’t seem to be supported by Plusnet).

• I’ve run multiple malware scans, monitored local traffic with Wireshark, and disconnected all devices—yet SenderScore still suggests a relatively high volume of outbound traffic.

I spoke to Plusnet support this morning. Nothing was resolved during the call, but they’ve agreed to investigate further.

[#8]

... but DKIM is support by Plusnet for Plusnet provided domains.

DKIM for a third party domain is not possible / practical.  If this is a reg123 provided domain ... why not just use their SMTP servers?

That said SPF should be fine.  This is a Gmail issue though.

[#9]

TBH this was all setup up years ago (10+) and until recently has just worked. I've had no need to make changes or use other SMTP servers. 

Why is it a Gmail issue?

[#10]

Mandating non-mandatory requirements on their free user accounts.

Send to a paid for @gmail.com or to the same addressee using @googlemail.com and there is no issue encountered.

Gmail has indeed deliberately broken a lot of what has worked for years, especially for volume senders. There are may references to the issues they have created, see Gmail Blocking Your Emails? Here’s How to Fix It (Feb 2024) amongst 1000's of articles.

This issue is far more difficult to fix where a sender opts to bounce their emails through a third party's SMTP service rather than using (paying for) the SMPT service provided by their domain hosting service.

[#11]

I just route my emails from username@mydomain.co.uk to user@username.plus.com 🤔

[#12]

“Just route” is where the problems start.

Why redirect? If the mail domain is hosted elsewhere use the hosting provider’s own mail services (or at least send emails via their SMTP server) that way all technical issues will be in the purview of the domain’s hosting service.

Mail redirection and hosting are not the same.

[#13]

As I say, this was all setup years ago... a lot of how it was done has fallen off my stack.

The domain was registered with 123Reg but is hosted by Plusnet. Going to [https://www.plus.net/my.html?action=domainv2] shows my domain.

I have a few mailboxes setup within Plusnet... the help text underneath states:

"If you have domain names on your account, the email addresses shown above will also be available for use with those domains. Just replace [username].plus.com with your domain name when setting up your mail software."

The nameservers on 123Reg were set to:

ns1.force9.net
ns2.force9.net

This setup worked until recently so I've had no need to seek alternatives.

[#14]

I am concerned that there is not a clear picture being communicated here; reviewing the whole of the post suggests various pieces of contradictory information...

@bornmild wrote:

No, I don't send high volumes of email - a maximum of 5 a day.

@bornmild wrote:

I send email from a hosted domain (hosted by 123Reg).

Graph shows nearly 200 per day!!  Be aware that this is an email count of what has been sent using the domain name - that does not mean that emails are going via the SMTP server you are using, but there is merit in changing the password for the account on 123reg.

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@bornmild wrote:

I don't believe I have a SPF record set. 

I can see a section on 123Reg where I can add DNS records... do I need to add a record of type TXT?

@bornmild wrote:

I've added the SPF record ...

All somewhat re-enforces the impression that this domain is hosted by 123reg and they run the name servers.

@bornmild wrote:

I just route my emails from username@mydomain.co.uk to user@username.plus.com 🤔

Fits the spoken narrative...

@bornmild wrote:

The domain was registered with 123Reg but is hosted by Plusnet. Going to [https://www.plus.net/my.html?action=domainv2] shows my domain.

The nameservers on 123Reg were set to:

ns1.force9.net
ns2.force9.net

This setup worked until recently so I've had no need to seek alternatives.

If that is correct, it entirely refutes everything told about the set up.

There is no redirection taking place here.

Configuring the 123Reg DNS will achieve ZERO to help you.

What does MXToolbox report about the domain?  If it is FULLY hasted by Plusnet, it should report...

• MX: mx.avasin.plus.net
• NS: (DNS Check)
  • ns1.force9.net
  • ns1.plusnet.co.uk
  • ns2.force9.net
  • ns2.plusnet.co.uk
• SPF: v=spf1 a mx include:_spf-internal.plus.net include:_spf-internal2.plus.net ~all

In which case everything is managed within Plusnet.  If all but the latter is there, you need to ask for the SPF record to be generated by PN's nameserver...

Mitigating email delivery failures (notably Gmail)

Many users are reporting challenging issues in sending emails to some of the big email players. Some of those providers (notably Gmail, but only in respect of their free email accounts) have mandated the SPF & DKIM non-mandatory RFCs on other email providers, such as Plusnet. This can bring about significant difficulty when attempting to send emails using the various Plusnet and vISP legacy email services.

How you mitigate Google's behaviour very much depends on how you send your emails via Plusnet's SMTP servers and which Plusnet vISP email brands you use.

• A Plusnet email account or a legacy brand (for example MAAF) email account
• you@youraccount.plus.com (native Plusnet email address)
• you@yourdomain.co.uk which is registered and hosted by Plusnet (or MAAF)
• you@yourdomain.co.uk which is registered elsewhere and hosted by Plusnet
• you@yourdomain.co.uk which is hosted elsewhere which forwards  mail to your Plusnet (or MAAF) mailbox

The vISP email brands have different level of mitigation capability - for some, the only practical solution might be to migrate your email hosting elsewhere.

Native Plusnet email address

If a user sends email using a from address of you@youraccount.plus.com then DKIM signing will be applied to the email automatically (and pass Gmail's imposed restrictions) if the SMTP server is configured to require authentication. Somewhat unhelpfully, Plusnet's email setup guide suggests that such authentication is NOT required if connecting over a Plusnet connection. Whilst technically true, operational complications can occur and it is much tidier to just enable authentication with the "use the same account settings as the incoming server" option.

Your own domain

If you send from your own domain name, then DKIM signing is not available and you will need to configure SPF instead. How to do this depends on where your domain is hosted - by Plusnet or by third party.

Plusnet fully hosted and registered domain

For Plusnet brand registered and managed domains, SPF configuration is facilitated by the addition of a TXT record in the domain's DNS settings. Plusnet's DNS configuration tool for hosted domains does not permit the creation of TXT records. However, there is an unsupported "facilitation" which will create an SPF record for a hosted domain.

On the basis that your account ALREADY has a hosted domain:

• Log into the user portal
• Go to Manage Account
• Manage Your Domains (Manage your domains link)
• Configure domain name
• Create an "Additional DNS records (Advanced)" as follows...

For the avoidance of doubt leave the left side blank, exactly as shown. It might take Plusnet's systems up to 6 hours to generate the SPF record.

If your email service is provided by one of the legacy vISP brands (for example MAAF) acquired over the years by Plusnet, similar options are not available to you.

Domain name registered and managed elsewhere (third party)

There are two scenarios here:

1. Plusnet hosts the email service for the domain
2. The domain forwards email to the native Plusnet email address

THESE ARE NOT THE SAME.  Ideally email forwarding should be avoided as it brings about numerous complications - you should use the DOMAIN's email servers to received and send your domain email, not Plusnet's.

To configure SPF on a domain name registered elsewhere, you must use your domain name provider's DNS configuration tools to set up the applicable SPF record:

v=spf1 a mx include:_spf-internal.plus.net include:_spf-internal2.plus.net ~all

or

v=spf1 include:_spf-internal.madasafish.com include:_spf-internal2.madasafish.com include:_spf-external.madasafish.com -all