If you’re seeing a lot of “451 4.7.500 Server busy. Please try again later” from Office365 this morning you’re not alone. Microsoft are aware of the issue, and incident EX680695 says: Current status: We’ve identified that specific IP addresses are being unexpectedly limited by our anti-spam procedures, causing inbound external email delivery to become throttled and delayed...
This is a followup from a post a few weeks ago about authentication changes at Office365. We have some more clarity on what is going on there. This is all best information we have right now. Microsoft is now requiring authentication to match the visible from address in order to reach the inbox at Office365. That means, either the SPF domain or the DKIM domain must align (in the DMARC sense) to...
A c/p from an email I sent to a mailing list. I think we’re seeing a new normal, or are still on the pathway to a new normal. Here’s my theory. 1) Hotmail made a lot of underlying code changes, learning from 2 decades of spam filtering. They had a chance to write a new codebase and they took it. 2) The changes had some interesting effects that they couldn’t test for and didn’t expect. They spent...
October was a busy month. In addition to on boarding multiple new clients, we got new desks, I went to Toronto to see M3AAWG colleagues for a few days, and had oral surgery. Happily, we’re finally getting closer to having the full office setup. What is an office without a Grover Cat? (he was so pleased he figured out how to get onto it at standing height). All of this means that blogging...
Microsoft is still in the process of rolling out new mail servers. One thing that is new about these is some new codes on their error messages. This has led to questions and speculations as to what is going on. host outlook-com.olc.protection.outlook.com [104.47.9.33] said: 550 5.7.1 Unfortunately, messages from [10.10.01.01] weren’t sent. Please contact your Internet service provider since...
While I was doing some research for a client today I rediscovered Terry Zink’s blog. Terry is one of the MS email folks and he regularly blogs about the things MS is doing with Outlook.com and Office 365. The post that caught my eye was discussing the Microsoft Spam Fighter program. The short version is that in order to train their spam filters, Microsoft asks a random cross-section of...
There’s been quite a bit of breakage and delivery failure to various Microsoft domains this month. It started with them changing the MX for hotmail.co.uk, then the MX for hotmail.fr… and both these things seem to have broken mail. I also saw a report this morning that some of the new MXs have TLS certificates that don’t match the hostnames. What’s going on? Historically...
Had a great time a M3AAWG last week. So many familiar faces and a lot of new ones, too. I’ve got a lot of interesting stuff that I can share with readers over the next few days. One of the things I have received permission to share is the new Office 365 IP delisting link. I botched the first time I posted it, so I’m going to try again. Office 365 IP Delisting Page. Many thanks to the...
I just saw a post over on the mailop mailing list where someone had been bitten by some of the IPv6 email issues I discussed a couple of months ago. They have dual-stack smarthosts – meaning that their smarthosts have both IPv4 and IPv6 addresses, and will choose one or the other to send mail over. Some domains they send to use Office 365 and opted-in to receiving mail over IPv6, so their...
The obvious application of machine learning for email is to send spam to the junk/bulk folder. Most services use some level of machine learning for filters. Places like Gmail have extensive machine learning filters to filter spam and unwanted mail away from their users. Some organizations are taking the filtering process a step further. Almost every mail client more advanced than PINE has the...
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