I need to put a message about this on our signup page (which means I need to figure out how to do that), but I thought I'd mention it:

Microsoft's servers almost always reject our mail, and there is no clear process for resolving this. We recently went to the trouble of setting up DMARC (which I still find baffling), but apparently they're still blocking us. I set up SPF years ago, too.

Microsoft's email services include, and apparently even some university systems (an email recently sent to showed that it was handled by a couple of subdomains of -- claiming that had been delivered, but probably to a spam folder).

(Also, just... don't use Microsoft products if you can avoid it.)

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@woozle For my information, which domain is this? I know that M$ and the Big G both have severe penalties on emails send from smaller domains, so it's useful to know. For example, sending from an *.xyz domain is really, really hard.

And ... good luck.


TootCat sends emails from (which is only available from a few registrars, hence not widely popular with spammers), but I have the same problem sending from .com and .org domains.

@woozle I've heard this a lot, and have ... I think ... experienced it from my own domain, ... sometimes emails just disappear.

@woozle this is an issue with all email addresses hosted by MS Exchange Online in addition to Microsoft's own domains, so not just certain universities but also countless businesses and other institutions that have outsourced their infrastructure to Microsift

They are the WORST...even worse than Google. Besides strictly enforcing SPF and DMARC they are also strict about having exacting PTR entries, using the proper TLS configuration, and appear to have some sort of block list of IP addresses that they deem to be in "dynamic IP blocks"

The process of making an email server worthy would certainly give Kafka inspiration and is certainly far in excess of what is required for spam control

@woozle also I see the typo at the end of the first sentence but leaving it because it is the most appropriate typo ever

@msh @woozle re: block lists, you can get your IP removed by request. Which isn't the way it should have to be but here we are.

And assuming you run your mail server. But start by requesting removal with Outlook sender support. They will deny it, but that's automated so reply to the email asking why and requesting a review. Someone will work to remove it for you.

@rob @msh That's the theory; in reality, it kind of doesn't actually work.

Also, the latest official support information I can find on getting unblocked doesn't mention there being a list; you're just supposed to fill out a support request form.

@woozle @msh it does work. I run a server at home and am no longer blocked.

And ya that's the starting point. They will reply that your not getting unblocked, but just reply and go from there.

If you want to see the conversation I can forward the email for reference.

@rob @msh It sounds like a huge nuisance -- but if it has worked for you, maybe I'll give it a try.

@woozle @msh oh it was a nuisance, and it made me mad that they just block everyone by default. That's not how mail is supposed to work.

@rob @woozle be aware the effect is not permanent; you may be arbitrarily blocked again by their automated systems as the rules and algorithms evolve. But yeah you can buy yourself a few years of trouble free time.

MSFT doesn't use public block lists from what I can tell. Instead they maintain their own. Ultimately the most reliable solutiom is to tell your contacts to explicitly add your email addresses to their own contacts, as that will override policies that dump your messages right into the spam folder (it is easier to make your emails not bounce but less so to keep them out of spam folders)

@msh @rob That was the unspoken fear lurking in the back of my mind... plus the fact that I do need to migrate servers every now and then, so the IP address will change.

I'm kinda more inclined to not waste the time, and just say that if Microsoft wants to defederate from the emailverse, let them -- just make sure everyone understands that this is a thing. :kestraglow:

@woozle @msh I agree, I tend to just tell people not to use any m$ mail or services. But there's always a few friends or family..
@woozle @msh maybe we should defederate with m$ 🤯 send them automated messages lol
@msh @woozle also though, your being blocked at the network level. So adding to contacts won't work, even replying to an incoming mail will fail.
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