Your methods and conclusions have merit. 😊
Aloha, Michael. -- Michael J Wise Microsoft Corporation| Spam Analysis "Your Spam Specimen Has Been Processed." Got the Junk Mail Reporting Tool<http://www.microsoft.com/en-us/download/details.aspx?id=18275> ? -----Original Message----- From: mailop <[email protected]> On Behalf Of Michael Rathbun Sent: Tuesday, September 25, 2018 3:04 PM To: [email protected] Subject: [mailop] Confirmation of Hotmail sending advice (was Re: Recent "banned sending IP" errors when sending to Microsoft) On Thu, 28 Jun 2018 19:25:12 +0000, Michael Wise via mailop <[email protected]<mailto:[email protected]>> wrote: >If you start to see 4xx deferrals (esp. 3113, 3114, 3115, 3150, …) from >the “Hotmail/Outlook/et al” data centers, you should know that the IP >has been throttled, and one would be well advised, given that >situation, to STOP all sending until at least the top of the hour, plus >a few minutes. And if the deferrals continue with THAT traffic, it is >strongly suggested that one hold off on any sending from that IP for at >least 24 hours. Bottom line is, right now, if you start seeing 4xx >deferrals from “HotMail” on a given IP, you should stop sending >immediately if you at all possibly can as it may affect the IP’s >reputation. But in general, if when you connect to a given mail server, >all you are seeing is deferrals, you should 1) notice, and 2) back off. A client recently notified us that he was seeing 100% deferral from Hotmail (and all the associated domains), and sought remediation advice. Remembering the above, I put in a throttle program that would cease sending for 4,000 seconds whenever more than 5% deferrals were seen in any given five-minute period when at least 20 delivery attempts were made. This did not remedy the situation, so we drained that queue into an unused IP and warmed it up gently; the traffic was then accepted without incident. After a couple days inactivity I began to trickle traffic back into the original IP, where it was also accepted without issue. I have configured their system for "minimum surprise". >And you should do some navel gazing to make sure those deferrals were not >happening for an as-of-yet un-noticed cause. Looking at the sending history of this client (verified opt-in, reasonably engaged, no sending to stale accounts, modest but bursty daily volume) my best conjecture is that their earlier configuration allowed a rather large inrush when a campaign began, and that recently this began to be considered abusive. mdr -- The Duckage Is Feep. -- Vaul Pixie _______________________________________________ mailop mailing list [email protected]<mailto:[email protected]> https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fchilli.nosignal.org%2Fcgi-bin%2Fmailman%2Flistinfo%2Fmailop&data=02%7C01%7Cmichael.wise%40microsoft.com%7C7498318a15074cd39a2708d62333a20e%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636735102023271706&sdata=SoBKFRgCvWg1i6O7uA3LswRpfjVIchYTNB%2BaRCHuCNA%3D&reserved=0
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