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

[#1]

---

Try removing the tick for..."

---

@Townman  @Dan_the_Van  @jab1 Doesn't help, messages still bounce.

[#2]

@Dan_the_Van 

That SPA is on the inbound server.  If I understand correctly, there is no issue connecting to the SMTP server.

The unanswered question is even though the server logins are using me@myaccount.plus.com is that also the from address used on the rejected delivery email?

@plusnettony is there anything on your radar which might explain this experience please?

[#3]

Nothing I'm aware of.

I'd try relay.plus.net, port 25, no outbound auth and give that a whirl while I ask about. 

Also, not sure if this still happens, but Outlook Express used to have a "feature" which made items in the outbox use the old settings even though you've changed them. Mail just used to sit there. Might be worth checking the outbox is empty, then change settings, then re-try a test email. 

[#4]

---

@plusnettony wrote:

..try relay.plus.net, port 25, no outbound auth...

---

No change, emails to @live.com still bounce.

---

...Outlook Express...

---

I'm not using Outlook express.  I'm using Outlook 2016 (version 2505) on my Windows 10 Desktop PC and logging in to webmail.plus.net on my Win 11 laptop.  In both cases, emails sent to @live.com or @outlook.com bounce instantly.  Emails to other domains do not bounce.

---

checking the outbox is empty, then change settings, then re-try a test email.

---

The outbox is empty, because the messages are sent but they are bounced instantly by the receiving MS servers.

Yes, I've tried restarting Outlook after I've OK'd any changes to the account settings.

EDITED TO ADD:

test messages that are automatically sent after I've made a change are being received.

[#5]

Sorry, to confirm I meant the feature from Outlook Express might be resident in the latest software.

I was going to raise a ticket asking for the bounce back but just wanted to confirm if the domain is with us, and on the same account?

[#6]

Hi All,

Thought I'd add to this thread rather than start new, but my parents (tech support son here!) are getting the exact same issue here when sending to Outlook accounts. For a little while now we both (my wife & I) have got the messages but in junk, but as of 2 days ago it seems they aren't getting through.

They are sending from two accounts, lets call these

DAD@THEIRUSERNAME.PLUS.COM

MUM@THEIRUSERNAME.PLUS.COM

and report issues sending via webmail, android (gmail app) and outlook (latest version, Win11)

I have asked them to try the SMTP authentication trick, but they report this does not work.

Oddly sending to GMail, and another Business email (microsoft hosted I believe) do work fine.

ERROR MESSAGE:

Reporting-MTA: dns; avasout-peh-002 [212.159.14.18]
Received-From-MTA: dns; [10.148.1.211] [146.199.91.0]
Arrival-Date: Tue, 17 Jun 2025 22:28:48 +0100

Final-recipient: rfc822; MYEMAILHERE@OUTLOOK.COM
Diagnostic-Code: smtp; 550 5.7.515 Access denied, sending domain THEIRUSER.PLUS.COM doesn't meet the required authentication level. The sender's domain in the 5322.From address doesn't meet the authentication requirements defined for the sender. To learn how to fix this see: https://go.microsoft.com/fwlink/p/?linkid=2319303 Spf= Fail , Dkim= Pass , DMARC= Pass [PA2PR10MB8395.EURPRD10.PROD.OUTLOOK.COM 2025-06-17T21:28:53.628Z 08DDAC6C3FABCD9D] [AS4P190CA0023.EURP190.PROD.OUTLOOK.COM 2025-06-17T21:28:53.653Z 08DDAABC8E491EB8] [AMS0EPF000001A9.eurprd05.prod.outlook.com 2025-06-17T21:28:53.653Z 08DDA99EB8E11330]

Last-attempt-Date: Tue, 17 Jun 2025 22:28:53 +0100

Happy to provide further deetails by PM if it would help anyone get this fixed. It's pretty annoying for them!

[#7]

---

@plusnettony wrote:

Sorry, to confirm I meant the feature from Outlook Express might be resident in the latest software.

---

It doesn't seem so.

---

confirm if the domain is with us, and on the same account?

---

I have no domain of my own.  My email address is simply [myName]@[myPlusnetUsername].plus.com and I'm at home, connected to the Plusnet servers via my router.  My Win 10 desktop has a wired connection to the router, my laptop uses wifi.

It's worked for years and years.

[#8]

I *think* I've been able to replicate this issue (either that or I can't spell hotmail). 

For reference, I've tried on webmail and got a bounce which I'm raising now to the relevant people. 

[#9]

My thanks to everyone who is trying to help with this problem. I'm glad to know that I'm not alone! I have also ticked 'My outgoing server (SMTP) requires authentication' and selected 'Use same settings as my incoming mail server'. No other options on that screen (Internet E-mail Settings) are selected. 'Log on using Secure Password Authentication (SPA)' on the POP3 screen is not selected. Emails to hotmail.com are still being rejected. I use Outlook and have also tried using webmail - same result. So far, emails to gmail are succeeding, but having read up round this issue I guess it's just a matter of time ...

Thanks again, everyone.

[#10]

I'm in exactly this situation.  As of 2 days ago, my father is unable to send emails from his plusnet email to my outlook email address and gets the bounce message as reported by others.  I only ever use outlook via the web interface so there is no receiving email client.  The error is encountered if sending from plus via email client or webmail.

[#11]

Thanks for raising the issues to us - I'll update this thread if I get news.

[#12]

---

@rjenkins123 wrote:

...the exact same issue here when sending to Outlook accounts...

...Oddly sending to GMail, and another Business email (microsoft hosted I believe) do work fine...

---

Yes, that, including the error message looks the same as my problem.

Prior to the problem appearing I had made no changes to my email settings, as I've already said it's worked for years and years.  Given that:

1. I conclude that MS have done something on their @live.com and @outlook.com servers that is resulting in messages coming from @[aPlusnetUsername].plus.com being rejected.
2. I also conclude that this is something that only Plusnet will be able to fix.

Does @plusnettony care to comment on my logic?

I can provide the bounce message if required.

[#13]

I suspect exactly that. 

I've got a bounce thanks, I'll let you know if I need more. Once I've raise, I'll provide the incident reference here too. Oddly, Force9 to Hotmail works fine. 

[#14]

Thanks.

I hope the fix isn't too long in coming.

[#15]

Hi guys, 

I've been asked for examples - if you could please drop me a PM with the bounce, this would be appreciated.