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Mail Delivery Failed - Outlook recipient

mayplace
Newbie
Posts: 1
Registered: 3 weeks ago

Mail Delivery Failed - Outlook recipient

I have been using PlusNet email for around 20 years, with a Thunderbird client on my Windows PC, currently still on a stable Window 7 version. I am a user@username.plus.com user, so directly with PlusNet.

Yesterday morning, for the first time, I received the following message:

Delivery to the following recipients failed permanently:

   * chrisgrose21@outlook.com

Reason: A message that you sent to the following recipient could not be delivered due to a permanent error. ** The remote server ?? responded with: ** chrisgrose21@outlook.com ??:?? This message was created automatically by mail delivery software on the server .
Final-recipient: rfc822; chrisgrose21@outlook.com
Diagnostic-Code: smtp; 550 5.7.515 Access denied, sending domain MAYPLACE.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 [GVYP280MB1070.SWEP280.PROD.OUTLOOK.COM 2025-06-17T08:47:16.043Z 08DDACF957D06E1B] [DUZPR01CA0315.eurprd01.prod.exchangelabs.com 2025-06-17T08:47:16.059Z 08DDAA1C7F3E2F05] [DB5PEPF00014B99.eurprd02.prod.outlook.com 2025-06-17T08:47:16.058Z 08DDA99F4C57979C]

The linked Microsoft fix was incomprehensible to me, so I turned to this site. I found a number of threads relating to a similar problem on GMail, although most of the discussion related to users with their own domains hosted by PlusNet. Nevertheless, I found some useful information, and changed my SMTP relay.plus.net settings to port 587, connection security to STARTTLS and Authentication method to Normal Password. I left User Name unspecified, since it hadn't been mentioned as part of the problem resolution. However, this hasn't solved the problem. I still get messages to outlook users (and one live.co.uk user) failing delivery.

Can anyone please help me fix the problem, and perhaps know what Microsoft (presumably) did yesterday to cause it?

 

 

5 REPLIES 5
Townman
Superuser
Superuser
Posts: 25,821
Thanks: 11,169
Fixes: 202
Registered: ‎22-08-2007

Re: Mail Delivery Failed - Outlook recipient

See https://community.plus.net/t5/Email/From-address-doesn-t-meet-the-authentication-requirements/td-p/2...

 

Microsoft have broken many third party email services... the business is examining matters.

Superusers are not staff, but they do have a direct line of communication into the business in order to raise issues, concerns and feedback from the community.

Jaclyn1
Newbie
Posts: 2
Registered: 3 weeks ago

Re: Mail Delivery Failed - Outlook recipient

Hi - My dad is having the exact same problem - he's uses his email to organise upcoming events in the town and has been unable to send emails to all customers/suppliers who are under the Microsoft banner - really hoping there is a simple fix as he's 77 and not tech savvy and I live 200 miles away from him. 

stuck
Aspiring Pro
Posts: 186
Thanks: 52
Registered: ‎21-05-2009

Re: Mail Delivery Failed - Outlook recipient


@Jaclyn1 wrote:

...hoping there is a simple fix... 


The topic linked to in the previous post is long but to understand why there is no simple fix that users can implement you need to read it all.

Yes, it's a massive pain but users can only wait until either email providers like Plusnet can come up with a fix and/or Microsoft adjust the requirements that has caused this outage.

SimonFastEddy
Hooked
Posts: 7
Thanks: 4
Registered: ‎14-02-2022

Re: Mail Delivery Failed - Outlook recipient

Hello Mayplace and Forum members,

I have the same issue: Fix NDR error 550.5.7.515 in Outlook.com

I discovered it today Thursday 19th June 2025 and is the same as reported elsewhere.

On my system, it affects just "To" Outlook.com and doesn't affect the HCC  Library public access computers.

eMClient and Thunderbird are affected similarly. Might be a Windows Update doing the wrecking.

Possibly a Microsoft problem. 

Nothing much that I can repair: the description forming a solution is drowning in a mess of technical terms.

Good luck!

SimonFastEddy

 

 

stuck
Aspiring Pro
Posts: 186
Thanks: 52
Registered: ‎21-05-2009

Re: Mail Delivery Failed - Outlook recipient


@SimonFastEddy wrote:

..Might be a Windows Update doing the wrecking.

Possibly a Microsoft problem. 


Not a Windows Update problem but it is caused by something Microsoft has done.

Read my post, the one immediately above yours.