topic Re: Not authorised error when sending from secondary mailbox to Gmail in Email

Not authorised error when sending from secondary mailbox to Gmail

dmitcalf — Sat, 14 Jun 2025 08:52:05 GMT

I created a secondary mailbox on my PN account some time ago but have just noticed this strange error. Mail sent from the secondary mailbox to any gmail address is rejected by gmail with a not deliverable response from gmail. I am using Apple Mail on a mac but I have also tried sending from webmail with the same result. Mail sent from the main mailbox gets through to gmail ok. I can send from the secondary mailbox to itself. I can also send from gmail to the secondary mailbox. Whats going on?

Re: Not authorised error when sending from secondary mailbox to Gmail

Townman — Sat, 14 Jun 2025 12:33:25 GMT

@dmitcalf

A warm welcome to the forums. What's going on is that Gmail is being bloody minded, mandating things which are not mandatory, albeit desirable. The answer to the questions below, might help identify a mitigation for their abhorrent behaviours...

If sending to fred@gmail.com if instead you send to fred.googlemail.com - does it get through
Are your sending as mailbox@account.plus.com or mailbox@yourdomain.co.uk
If the latter, is the domain hosted by Plusnet or elsewhere with forwarding to Plusnet
Is the SMTP server connection using your (secondary) email address for authentication (or account+mailbox)
Is the SMTP server connection using port 587 with STARTTLS encryption

Re: Not authorised error when sending from secondary mailbox to Gmail

RealAleMadrid — Sat, 14 Jun 2025 13:15:23 GMT

@Townman In question 1 shouldn't the alternative address be fred@googlemail.com ?

Re: Not authorised error when sending from secondary mailbox to Gmail

Townman — Sat, 14 Jun 2025 13:16:58 GMT

Yes - thank you for highlighting the typo!

Re: Not authorised error when sending from secondary mailbox to Gmail

dmitcalf — Sat, 14 Jun 2025 18:55:05 GMT

Hi Townman, thank you for your reply. Sending to fred@googlemail.com works - the message gets through ok. I was using fred@mydomain.com with my domain.com hosted by PN. I am using account+mailbox for authentication and the port number used for outgoing mail is via relay.plus.net on port 587

Re: Not authorised error when sending from secondary mailbox to Gmail

Townman — Sat, 14 Jun 2025 19:05:34 GMT

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:

Plusnet hosts the email service for the domain
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

Re: Not authorised error when sending from secondary mailbox to Gmail

dmitcalf — Mon, 16 Jun 2025 11:24:41 GMT

Created the DNS record as detailed above but doesn’t seem to have been actioned. No SPF records yet and the problem still persists. Guess this is a manual process so they need a few working days?

Re: Not authorised error when sending from secondary mailbox to Gmail

MisterW — Mon, 16 Jun 2025 11:37:35 GMT

@dmitcalf

Guess this is a manual process so they need a few working days?

It's an automated process BUT the script only runs every 6 hours IIRC. Have you created the DNS record EXACTLY as described i.e priority and right field ?

Re: Not authorised error when sending from secondary mailbox to Gmail

dmitcalf — Mon, 16 Jun 2025 11:59:17 GMT

The priority had too many 9s, could that be it? Did it again just to be on the safe side

This is the latest

Re: Not authorised error when sending from secondary mailbox to Gmail

Townman — Mon, 16 Jun 2025 12:16:47 GMT

If what you configured was not EXACTLY as advised, then it is not likely to work. The unsupported facilitation is not forgiving of errors!

Re: Not authorised error when sending from secondary mailbox to Gmail

dmitcalf — Mon, 16 Jun 2025 16:15:20 GMT

Working now. Thanks for all your help