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Josh RogalskiFlag for United States of America

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Yahoo Email Failing to send to Office 365

We have Microsoft Office 365 as our email provider.  A good amount of people sending from Yahoo based email accounts (including those who lease yahoo servers) cannot send to us.  They sometimes get a bounce back message which I have attached.  I am looking for any assistance as Microsoft and Yahoo are extremely difficult to get support from.  The error message in the bounce back comes from Yahoo's Mailer Daemon, and tries several times to send.  

Any assistance would be appreciated.  Thank you!
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David Favor
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To understand why this mail wasn't delivered, you require the actual SMTP code sent from Microsoft Office 365 back to Yahoo at the time of the SMTP conversation.

This may be impossible to get.

You'll have to look for either raw SMTP log access in your Microsoft Office 365 account or open a trouble ticket with Microsoft Office 365 asking for the SMTP information.
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One interesting part of this, it appears that the message NEVER even makes it to Microsoft's servers.  When you search for it, it never appears to see any communication between the two.  I tested AOL and straight Yahoo emails and those made it through.  I am wondering if certain people have mail clients configured on their computers or phones and a possible misconfig or old configuration is causing this.  More investigation is necessary I think.
Then the IP you're using at Microsoft may have ended up on an RBL list.

You'd think this should never happen + it does sometimes.

You might try creating a Yahoo account + sending to one of your Microsoft Office 365 accounts.

If you can somehow extract the SMTP transaction data from the Yahoo side, this will help debug the problem.
Something interesting that we discovered, we had another campus user who uses AOL for personal email (which is housed by Yahoo servers).  Same issue, same message.  I had them stop using their built in IOS app, and instead use the AOL app for IOS and the messages work.  Very odd.  Addtionally, I was able to get the bounce back message.  Hoping something can be seen from it.  It is attached.
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David Harbaugh

We're still having this issue, and I desperately need a solution.  The failure notice the user is receiving (with names changed to protect the innocent) is below:

Date: January 16, 2018 at 2:24:21 PM EST
Subject: Failure Notice
Sorry, we were unable to deliver your message to the following address.

Unable to deliver message after multiple retries, giving up.

--- Below this line is a copy of the message.
This is simple to debug.

The MTA handling mail for domain has no record for the user cayuga_user, so the owner of the domain must review their MTA logs to determine + fix the problem, if the user cayuga_user really exists.

You'll contact the owner of the domain to resolve this problem.

Note: Only the MTA logs will explain the problem.
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Josh Rogalski
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