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I am having issue that Yahoo emails are not reaching recipients. I am getting an error message but after 24hrs not even straight after. It's only come to my attention because in follow up calls, they are telling me that the emails never arrived..
Please advise me how to sort it out as is very important I can reach those yahoo recipients.
Your message couldn't be delivered. Despite repeated attempts to contact the recipient's email system it didn't respond.
Contact the recipient by some other means (by phone, for example) and ask them to tell their email admin that it appears that their email system isn't accepting connection requests from your 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 more information and tips to fix this issue see this article: https://go.microsoft.com/fwlink/?LinkId=389361.
Using classic Outlook for Windows in business environments
Locked Question. This question was migrated from the Microsoft Support Community. You can vote on whether it's helpful, but you can't add comments or replies or follow the question.
Microsoft says it's not their issue. Yahoo is requiring additional security from senders to their service. Why and why all of a sudden is the question.
Implementing DKIM on the Microsoft side and adding the DNS records on the sender's domain DNS fixes the problem.
Thanks. That did the trick.
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I don't see Microsoft mail hosting service as a factor in this problem. The root cause of the problem is custom or private domain names not having correct DNS records and recipient's SMTP servers recent change to enforce those records. The mail hosting service can be any company... Microsoft, Google or any 3rd party mail hosting company or yourself if you host an on-premise mail servers.
I don't know what you've seen but I have a number of clients using various email services and in-house mail servers that have no problem sending to Yahoo without DKIM. SPF isn't necessary if you're sending from your own server anyway (of course, there are other requirements like Reverse PTR, proper HELO statements). But from what I see, this is clearly an issue between Microsoft and Yahoo and its cohorts (AOL, Verizon, etc.).
It has always been a free-for-all when it comes to security requirements when sending to various mail servers. There are hundreds of blacklists that can be subscribed to. Most servers don't validate against more than three. Which three? Exactly. Then there's the heuristics. Yet another black hole.
If you look at Yahoo's "Sender Best Practices" they still state that SPF *or* DKIM is required for non-bulk senders. None of my clients send bulk mail through their official email domain.
I don't mind increasing security but I'm not a fan of these companies moving the goal posts without sufficient warning.
>> SPF isn't necessary if you're sending from your own server anyway
SPF record lists all servers (or IPs) authorized to send email on behalf of your (private) domain name. I don't see why you don't need SPF if you host your own mail server. Without it spammers can spoof your domain name to send spam from their SMTP servers (or botnets). I used to host my own Exchange server and I created an SPF record for the company domain. That tells recipient SMTP servers my email can only come from these authorized IPs (defined in the SPF). Whether or not recipient's SMTP servers verify SPF record is another story.
>> But from what I see, this is clearly an issue between Microsoft and Yahoo and its cohorts (AOL, Verizon, etc.).
That's incorrect. Some users don't even use Microsoft hosting service and their email are still rejected (due to invalid or missing records). That's why I said I don't see Microsoft hosting service as part of the problem. It's DNS record problem. It isn't mail hosting service or company.