From address doesn't meet the authentication requirements defined for the sender

[#1]

Just to add I've also had this error come up just now. following...

[#2]

I have just received the following bounce back when e-mailing a friend who uses icloud.com e-mail:

Reporting-MTA: dns; avasout-peh-002 [212.159.14.18]
Received-From-MTA: dns; DESKTOPxxxxx [xxxxxx]
Arrival-Date: Thu, 19 Jun 2025 21:34:56 +0100

Final-recipient: rfc822; xxxxx@icloud.com
Diagnostic-Code: smtp; 554 5.7.1 [HM08] Message rejected due to local policy. Please visit https://support.apple.com/en-us/HT204137

Last-attempt-Date: Thu, 19 Jun 2025 21:35:04 +0100

This is becoming a serious issue for me. Does anybody know what action plus.net is taking please?

Thanks.

[#3]

@ebforum Reading up on that 554 code, it appears that the fault/problem is at the recipients end - so nothing to do with Plusnet.

I usually find that a quick Google can, on occasion, be useful.

[#4]

It's not as simple as saying that the issue is at the receivers end.

PlusNet, rightly or wrongly have emails setup in such a way that they are sent without a valid SPF - which is a way of saying "these are the people allowed to send from my domain". It has been pointed out that PlusNet do have other, arguably better, security/antispam methods which historically have been fine.

However, Microsoft have recently implemented a policy that for bulk senders, no SPF = mail returned to sender. Microsoft have also identified PN as a bulk senders as there are presumably thousands of users sending from emails ending ***.plus.com. Arguably Microsoft should be applying the bulk sender check to ***username.plus.com however they are not and that is what it is.

It's semantics to say who is at fault here - the reality however is that Microsoft are dominant, and you can bet that over time their rule will be rolled out to a) non bulk senders (so even if they were to run the check at a subdomain level), and b) other email providers - interesting to see someone saying they get the same issue with iCloud now.

So, fair or otherwise, Plusnet really need to sort the backend of this fast. There isn't (and maybe a super user or staff) could confirm, anything an individual can do to avoid this

Would be great to get an update on ETA for a fix - as this is pretty terminal otherwise and many users will have no option to use another email address.

[#5]

There isn't (and maybe a super user or staff) could confirm, anything an individual can do to avoid this 

Correct, there isnt.

[#6]

Correct, there is nothing end users can do.  The reality is that Microsoft has got this wrong, passing a significant workload on to mail providers.  Either SPF or DKIM is more than adequate.

Bundling individual users into the same bulk sender bundle is utter nonsense.  This is clearly a measure to address the bulk marketing abusers but has unwittingly caught domestic mail service providers.  Microsoft’s solution should facilitate the recognition of domains to be excluded.

We need to see this for what it is, a blatant ruse to drive users to Microsoft’s email platform.  It is no different to experience elsewhere: my church’s email service is hosted on AWS which Microsoft has black balled - similar to here we cannot email to MS users and we are using both SPF and DKIM.  Unfortunately our email provider’s solution is to move to Microsoft 365 hosting,

People must wake up, smell the coffee and recognise who is the real villain here.

[#7]

Very well said, @Townman  - I agree 100%, as anyone with an ounce of common sense should.

[#8]

Does anyone here have an understanding of how much work it would entail for plus.net technical staff to implement the changes necessary to accord with whatever Microsoft has done?

Also, surely a company like plus.net has a contact at Microsoft to enable them to discuss the problems their customers are facing and to see if there is a temporary workaround Microsoft can apply to let plus.net domain e-mail through their system.

[#9]

@ebforum, I've only been partially following this so may have this wrong, which @Townman or @MisterW will be able to correct me on if I have.  The amount of work required by Plusnet is relatively small, and is something that was attempted quite a while ago.  The implications of doing so though is that it would break email sending for the many thousands of users who don't use the Plusnet relay servers for them to send to most addresses.

[#10]

@pjmarsh 

The amount of work involved is I believe under discussion.  This will not just the the technical implementation requirement, but also the forma change controls and support staff briefing / training to deal with the consequential issues.

@ebforum 

Plusnet's email implementation has allowed a great deal of flexibility for the user base, some of which one could argue as being counter productive.  Personally I see no merit in allowing users the ability to send the email of their domain through some other provider's SMTP relay services.  SPF implementation has been attempted previously (in response to Gmail's draconian measures) and many users operating 'outside of the box' hit sever issues.  I suspect that the effort to address those users' issues was deemed disproportionate to the benefit, considering that (on reflection) DKIM could be implemented easily being more than adequate for the prevention of SPAM / mitigating Gmail's blight.

Microsoft's action here is truly OTT and mitigating it is likely to involve a deal of pain all around.

[#11]

@pjmarsh that's about right. It requires an SPF record to be created for every account subdomain i.e <accountname>.plus.com. AIUI the DKIM & DMARC records can be on the parent domain and already exist, but the SPF record must be on the subdomain.

As you say , its not difficult to automatically create a 'standard' SPF record for every account , which specifies the Plusnet relays as permitted senders. The problem is , there is no way for the user to change the SPF record if they dont use the Plusnet relays, so in that case it would break their sending of email. The thing is, though, is their sending from a native <account>.plus.com via their own server (with no SPF record or DKIM) already broken anyway ? 

well at least to Microsoft/Google and  probably to most recipients sooner or later...

[#12]

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@rjenkins123 wrote:
Would be great to get an update on ETA for a fix.

---

@Townman @MisterW @plusnettony I don't expect a definitive answer to that request but can you at least hint if we are likely to be waiting:

• up to 2 weeks?
• up to a month?
• longer?

My current broadband contract expires soon so any clues will help me decide whether to renew or, after 16 years, leave PN.

[#13]

I am sorry, at this stage I don't have an answer for that. 

[#14]

If you’ve been happy with the broadband service it would seem perverse to leave because of an email issue inflicted on a third party.  Such a move would require you to find an alternative email provider … which you could consider whilst remaining here for the broadband service.

i have asked for an update.

[#15]

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@Townman wrote:

...it would seem perverse to leave because of an email issue...

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Yes perhaps but in my case there's more to it.  Specifically that my better half would dearly love to retain a land line, and since PN will stop providing that service in the near future I'm already halfway to the exit.  That the MS accounts I can no longer reach as those of my children is just another couple of steps nearer the door.