Emails from Outlook bounce back from all yahoo and sky emails with error message

I am having the same issue.

Anything sent to a @yahoo.com email address is now bouncing back as of Saturday 9th March 2024.

Previously we have been able to send emails to the email addresses in question.

On Thursday 7th March 2024, our Microsoft Office 365 licences were upgraded from Business Standard to Business Premium which now allows us to use Microsoft Defender.

My thoughts are that it is related to this somehow.

Any news yet Microsoft?

I am having the same issue.

Anything sent to a @yahoo.com email address is now bouncing back as of Saturday 9th March 2024.

Previously we have been able to send emails to the email addresses in question.

On Thursday 7th March 2024, our Microsoft Office 365 licences were upgraded from Business Standard to Business Premium which now allows us to use Microsoft Defender.

My thoughts are that it is related to this somehow.

Any news yet Microsoft?

Josh, just seen your message following mine. I think you are correct - it's looking like it is to do with outgoing email signing ie SPF, DKIM and DMARC records.

https://answers.microsoft.com/en-us/msoffice/forum/all/spf-and-dkim-records-how-do-i-find-out-what-they/20341215-ea7d-42f8-8a96-9e947ea333ce

I am looking at ours this morning to check/test

Hello

 

Good day.

Thank for posting in the community.

 

We've received your query and you can expect to receive response from one of our community moderator accordingly.

 

At this point, we appreciate your patience and cooperation. Thank you.

 

Sincerely,

Community moderator 

This morning I received calls from 3 clients with the same issue.

We have also received multiple calls from our clients experiencing the same issue, yahoo and aol specifically.

error message "Your message wasn't delivered. Despite repeated attempts to deliver your message, a connection to the remote server was closed abruptly.

Contact the recipient by some other means (by phone, for example) and ask them to tell their email admin that it appears that your email system is unable to connecto their email system. Give them the error details shown below. It's likely that the recipient's email admin is the only one who can fix this problem.

For Email Admins
This often indicates the recipient's firewall SMTP fixup setting or other firewall settings are preventing the SMTP protocol negotiation from succeeding.

For more information and tips to fix this issue see this article: https://go.microsoft.com/fwlink/?LinkId=389361.

For Yahoo: returned '550 5.4.318 Message expired, connection reset (SuspiciousRemoteServerError)(450 4.4.318 Connection was closed abruptly (SuspiciousRemoteServerError))'
3/8/2024 8:44:42 PM - Server at mx-eu.mail.am0.yahoodns.net (188.125.72.73) returned '450 4.4.318 Connection was closed abruptly (SuspiciousRemoteServerError)'

For sky: returned '550 5.4.300 Message expired -> 421 4.4.2 Connection dropped due to SocketError'
3/8/2024 8:39:33 PM - Server at 188.125.72.73 (188.125.72.73) returned '421 4.4.2 Connection dropped due to SocketError'

I cannot ask all my contacts that have yahoo or sky accounts to change their firewall settings. There seems to be a problem with Microsoft!

I am using Outlook through GoDaddy and eventually found a solution via another post to Microsoft Community Forum in January. "Enable and add DKIM to my domain for Microsoft 365"

https://www.godaddy.com/help/create-and-add-dkim-records-to-my-microsoft-365-organization-41748.  It worked! I think it only applies to GoDaddy, but there must be similar solutions out there for other providers. Why do we have to sort this out for ourselves? I am not an IT expert and I have wasted hours of my time. The GoDaddy support advisor could only offer me to use MailChimp instead. Does Microsoft not have anyone watching these post and can offer a solution in plain English. GoDaddy said it is only going to get worse as more security protocols are introduced to prevent spam.

Dear Admin Act for Inclusion,

Thank you for visiting Microsoft Community, we are glad to assist you here.

Please kindly note this is a known issue as Yahoo made an authentication change, requiring email senders to strongly authenticate their emails following well-established best practices such as DMARC, SPF, and DKIM.

Please follow the steps to enable it as below:

Set up SPF identify valid email sources for your Microsoft 365 domain | Microsoft Learn

How to use DKIM for email in your custom domain | Microsoft Learn

Use DMARC to validate email, setup steps | Microsoft Learn

Email authentication in Microsoft 365 | Microsoft Learn

For your reference:

Authenticate Outbound Email to Improve Deliverability - Microsoft Community Hub

If still same issue, it is suggested to open ticket and contact Microsoft Technical team Get support - Microsoft 365 admin | Microsoft Learn to get further assistance on this query.

Thank you for your time.

Please feel free to get back to us if you have further concerns,

Regards,

Microsoft Community