This has plagued us for years. We send quite a lot of transactional email (about 150k emails per day), and there have been several times where Microsoft blocked our server. Usually it is because Microsoft has banned an entire netblock, that our server just happens to be sitting in. I have seen them do this to IPs fro Hetzner, Linode, Amazon AWS (SES), etc. And yeah we've signed up for their junk mail reporting service, and we have all our DNS records dialed in perfectly.
I even went as far as signing up for Azure, in the hopes that if I sent from a Microsoft IP it might not get blocked. But I didn't make it very far, every step of the way was like watching paint dry while the interface loaded or did something. Once I finally got the thing set up in order to send mail, the API was so molasses slow that it couldn't handle our mail throughput. Meaning it would take about 30 seconds to send each transactional email because of how slow their API is. Well that's only 2880 emails per day, that is not a reasonable send rate at all.
I have even lost customers over this mess, it's really hard to explain to them that they can't receive our email because of their provider and not us. Especially when Microsoft has the audacity to return: 250 OK Email Queued (but then not deliver it anyway!)
If anyone has any solutions to this mess I am all ears!
There's like a middle scale where you're not big enough that Microsoft will go out of their way to whitelist you, but you're big enough that your "send to junk" rate is just high in terms of absolute numbers.
It's certainly not a ratio, it must be based on absolute numbers because I've seen it too many times across too many companies, and the only ones that get away with it are extremely low volume.
Once you have 1,000,000 mails, even a 0.1% mark as spam rate is 1,000 emails. - and some people treat mark as spam as their delete button, certainly more than 0.1% of people. Don't ask me why.
EDIT: on inspection; it's worth noting the mechanism is even more insidious than "people mark you as spam". Microsoft also weighs delete-without-opening as a negative signal. So if you're sending transactional mail (receipts, shipping notifications, invoices) and your users get exactly what they wanted, feel satisfied, and bin it without opening. You've just taken a reputation hit for doing your job correctly. The senders most at risk aren't the ones sending rubbish.
EDIT2; theres a reply to me that I can’t reply to because its [dead]; though the point is valid so I vouched. To them I say: I agree. But you probably want your receipt, and thats the example I gave (for a reason).
Once when this happened to me a couple of years ago, it was the opposite.
My e-mails were put by default by Microsoft as spam into the junk folder, without the customer knowing anything about this.
After I succeeded to notify him about this, he searched there the e-mails and marked them as "not spam", and then he received my following e-mails.
So initially the customer did nothing and was not aware that some of the e-mails sent to him are classified as spam, and he had to do active efforts to override this default action by Microsoft.
There was absolutely nothing suspicious about the e-mail messages classified as spam in their content, their only fault was not coming from one of the few major e-mail providers.
Almost certainly not.
Microsoft was the only email provider we had problems with a few years back. We only sent emails to people who paid us several hundred USD to send that email. We didn't sent anything else - no follow ups, marketing, announcements, nothing.
That should allow you to be more proactive about users reporting your messages as spam, either intentionally or unintentionally.
FWIW: We've been sending Microsoft properties e-mails for over a decade, fairly small scale (maybe 5-20K unique recipients at MS properties in a month), and every 2-4 years we have to submit our IP to their "whitelist me" site and then we're golden again.
This time was different, when we submitted our IP to the whitelist site it said "Nothing is blocking your ability to send to us". They did end up responding to our whitelist request a week later asking if we were good or still needed help, which is a first.
They also block people who send very little mail. If you only send one or two per month to their consumer domains you don't build enough 'reputation'.
I know for a fact my mail server never sent any spam because I logged everything. It was only me using it. But every few months I got banned from sending to live.com. I have one friend there. They didn't mark anything as spam. We just sent personal emails.
There's a form where you can unban it but it kept happening. In the end I stopped running my own, it was so much hassle.
It is my experience, that Outlook is not a reliable e-mail service. Sometimes e-mails are not delivered, or only delivered hours later. When they are delivered, even as a paying customer, they are downloaded so slowly, that I had to wait 10 minutes to get all my e-mails, while my 1 EUR per month Posteo provider delivers in seconds.
My impression is, that the only reason one would want to have MS as a mail provider is, that they are entrenched in the e-mail provider reputation and delivery game. Other than that, it seems to be an all around bad service. Not even talking about the mail client itself.
The big reason is enterprises buy into O365 and running their email through Outlook instead of on-prem or at another provider is part of that. For the same reason they use Teams over Zoom or Slack or other alternatives.
My clients have been experiencing this forever; the logs SAY "temporarily rate limited due to IP reputation." but really the emails are never going to get delivered. I have to get MailChimp or Mailgun to rotate the IPs.
It looks like all it takes is one person to mark your email as spam, even by accident. Note that these are mailing lists which they signed up for in MailChimp case OR transactional emails in the Mailgun case.
It's only hotmail/outlook that we constantly have this issue with, Google etc. are all fine.
Often these "spam" reports by end users are just accidental clicks as well. Many of the abuse reports we get are like an email from someone's Mum and visibly legitimate. At other times there are users who use the Report Spam function as a kind of inbox management tool - a way of moving mail away so they don't have to see it because Trash or Delete or whatever is just further away from their pointer.
I tell my friends and family to never click unsubscribe links, unless they had proactively subscribed. Buying something from a company that requires an email does not count. unsolicited marketing emails are spam and should be treated as such. Double so if that company sends marketing emails disguised behind support@company.com.
"Report spam" is quicker and easier than "unsubscribe".
Gmail added a popup asking the user if they want to unsubscribe when flagging a newsletter with the appropriate unsubscribe headers, so it must be common enough to warrant Gmail developer attention.
Agreed. I was an early outlook.com user (was working at MS when it launched, I think internal users got slightly early access allowing me to claim a nicer name than my Gmail) but despite having well over a decade of accounts tied to it got so angry at certain messages never appearing that a couple of years ago I reversed the flow of forwarding and swapped to another account as my primary.
I always thought of outlook.com as a rebranding of Hotmail (which itself had been continually evolving, was probably actually “Live” at that point), I would expect it is the same (ever evolving) infrastructure.
In which case, people like me with an @hotmail.com address from the 90’s were much earlier users of the outlook.com email boxes than when the domain was “launched” by Microsoft.
As long term Outlook.com user all I can say it's their service is extremely unreliable, my emails are either not delivered at all or end up in junk mail, some emails I don't receive at all or my partners are rate limited sometimes receiving their emails with hours long delays.
I assume also their junk filters block some emails and there is no way to avoid it, you repeatedly add senders to safe senders list, even to safe subscriptions and their email still end up marked as junk even after years long communication from same addresses.
As backup when something important I write email to recipient from gmail whether they received my email from outlook only to find out my email was never received.
It feels like there's quite a lot of spin on this. There's no hint as to how many users were actually affected. It only really seems to mention Estonia, and probably only a region of it.
The ISP there claims they haven't received any reports of SPAM. But that sounds wrong. No reports probably means your reporting system is broken.
So putting that together, it seems like a small ISP screwed up and let spammers go wild, and Outlook blocked them for it. I can't really fault Outlook for that.
Someone recently leveraged some kind of automated spam attack against my domain using Zendesk's email servers. For some reason, Zendesk doesn't enforce SPF and DKIM checks when opening new tickets, so I got flooded with "your new account has been registered" and "thank you for filing a ticket" emails.
I blocked off Zendesk entirely because they didn't fix their shitty email system. The other newsletter mail services (mailgun/sendgrid/etc.) are just as bad for this.
There are plenty of reasons why large email senders could (and should) be on reputation blacklists. None of these email delivery companies seem to care very much about the spam they send until shit hits the fan, and now that it did it seems everyone blames the people maintaining the blacklists.
This was widespread, I was also affected. I think you can create spoof tickets / accounts over Https with no verification and zendesk don't want to do anything which adds friction.
My org (USA) was affected. I wasn't the primary person dealing with it, but from what I gather one user marked one of our emails as junk, and then suddenly all of our emails to Outlook users started getting blocked.
One IP address (exclusively ours) among our email IPs at my place of employment was affected. We have used that IP for nine years. Emails are strictly transactional (receipts, password resets, et cetera).
The "rate limiting" started two weeks ago, giving us a code that Microsoft's documentation doesn't even list. It remains unresolved. Never had critical issues like this on our transactional IPs prior to this, and this particular IP address is still delivering just fine to other consumer and corporate email systems.
Your intuition is way off, like dangerously off. But your comment is a great example to show a smug lawyer at Microsoft when they try to say there is no basis for the claim that these blocks against legitimate senders are defamatory.
This has been affecting reputable senders who take spam reporting seriously, including MXRoute and Discourse.
> No reports probably means your reporting system is broken.
"No reports" can mean a lot of things. There is no "probably".
The "you" in "your" is Microsoft because under a certain volume of email, they don't even send reports. I regularly test the abuse contact address for my server because of this exact unfair assumption - that it must be my fault. I have never once gotten an abuse report notification from Microsoft, but I have gotten a bounce message saying that I'm blocked because I apparently send spam! Btw, this was in reply to an email from a Microsoft user.
Worse, I figured I'd just disallow any email from a Microsoft property - if an outlook (or hotmail or live or anyone else) sends an email, I can just bounce it and tell them to use a different service to reach me since I can't reply. Nope! Microsoft won't surface the bounce message to the user.
So, I am barred from replying to Microsoft emails. I am also barred from informing the sender that their email won't reach me.
It's defamation - the sender is always going to assume that it is my fault if I didn't reply even if the reason I "didn't reply" is outside of my control.
> So putting that together, it seems like a small ISP screwed up and let spammers go wild, and Outlook blocked them for it. I can't really fault Outlook for that.
Yes, in your imagined scenario, you can't really fault outlook. In the real world, however, outlook is very much to blame.
This is an extremely widespread issue. I send close to a million emails per month across dozens of different providers (all newsletters.) These are all from high reputation domains and email accounts. We are completely unable to make anything happen with Microslop. It is infuriating.
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I even went as far as signing up for Azure, in the hopes that if I sent from a Microsoft IP it might not get blocked. But I didn't make it very far, every step of the way was like watching paint dry while the interface loaded or did something. Once I finally got the thing set up in order to send mail, the API was so molasses slow that it couldn't handle our mail throughput. Meaning it would take about 30 seconds to send each transactional email because of how slow their API is. Well that's only 2880 emails per day, that is not a reasonable send rate at all.
I have even lost customers over this mess, it's really hard to explain to them that they can't receive our email because of their provider and not us. Especially when Microsoft has the audacity to return: 250 OK Email Queued (but then not deliver it anyway!)
If anyone has any solutions to this mess I am all ears!
Once enough of your customers do this to cross a certain threshold, you are identified as an undesirable sender and QED.
There's like a middle scale where you're not big enough that Microsoft will go out of their way to whitelist you, but you're big enough that your "send to junk" rate is just high in terms of absolute numbers.
It's certainly not a ratio, it must be based on absolute numbers because I've seen it too many times across too many companies, and the only ones that get away with it are extremely low volume.
Once you have 1,000,000 mails, even a 0.1% mark as spam rate is 1,000 emails. - and some people treat mark as spam as their delete button, certainly more than 0.1% of people. Don't ask me why.
EDIT: on inspection; it's worth noting the mechanism is even more insidious than "people mark you as spam". Microsoft also weighs delete-without-opening as a negative signal. So if you're sending transactional mail (receipts, shipping notifications, invoices) and your users get exactly what they wanted, feel satisfied, and bin it without opening. You've just taken a reputation hit for doing your job correctly. The senders most at risk aren't the ones sending rubbish.
EDIT2; theres a reply to me that I can’t reply to because its [dead]; though the point is valid so I vouched. To them I say: I agree. But you probably want your receipt, and thats the example I gave (for a reason).
Once when this happened to me a couple of years ago, it was the opposite.
My e-mails were put by default by Microsoft as spam into the junk folder, without the customer knowing anything about this.
After I succeeded to notify him about this, he searched there the e-mails and marked them as "not spam", and then he received my following e-mails.
So initially the customer did nothing and was not aware that some of the e-mails sent to him are classified as spam, and he had to do active efforts to override this default action by Microsoft.
There was absolutely nothing suspicious about the e-mail messages classified as spam in their content, their only fault was not coming from one of the few major e-mail providers.
That should allow you to be more proactive about users reporting your messages as spam, either intentionally or unintentionally.
FWIW: We've been sending Microsoft properties e-mails for over a decade, fairly small scale (maybe 5-20K unique recipients at MS properties in a month), and every 2-4 years we have to submit our IP to their "whitelist me" site and then we're golden again.
This time was different, when we submitted our IP to the whitelist site it said "Nothing is blocking your ability to send to us". They did end up responding to our whitelist request a week later asking if we were good or still needed help, which is a first.
I know for a fact my mail server never sent any spam because I logged everything. It was only me using it. But every few months I got banned from sending to live.com. I have one friend there. They didn't mark anything as spam. We just sent personal emails.
There's a form where you can unban it but it kept happening. In the end I stopped running my own, it was so much hassle.
My impression is, that the only reason one would want to have MS as a mail provider is, that they are entrenched in the e-mail provider reputation and delivery game. Other than that, it seems to be an all around bad service. Not even talking about the mail client itself.
It looks like all it takes is one person to mark your email as spam, even by accident. Note that these are mailing lists which they signed up for in MailChimp case OR transactional emails in the Mailgun case.
It's only hotmail/outlook that we constantly have this issue with, Google etc. are all fine.
Gmail added a popup asking the user if they want to unsubscribe when flagging a newsletter with the appropriate unsubscribe headers, so it must be common enough to warrant Gmail developer attention.
Sounds like it's gotten even worse.
In which case, people like me with an @hotmail.com address from the 90’s were much earlier users of the outlook.com email boxes than when the domain was “launched” by Microsoft.
Deleted Comment
I assume also their junk filters block some emails and there is no way to avoid it, you repeatedly add senders to safe senders list, even to safe subscriptions and their email still end up marked as junk even after years long communication from same addresses.
As backup when something important I write email to recipient from gmail whether they received my email from outlook only to find out my email was never received.
These are emails that our customers have specifically requested and we get support tickets blaming us.
It's been like this for years.
The ISP there claims they haven't received any reports of SPAM. But that sounds wrong. No reports probably means your reporting system is broken.
So putting that together, it seems like a small ISP screwed up and let spammers go wild, and Outlook blocked them for it. I can't really fault Outlook for that.
I blocked off Zendesk entirely because they didn't fix their shitty email system. The other newsletter mail services (mailgun/sendgrid/etc.) are just as bad for this.
There are plenty of reasons why large email senders could (and should) be on reputation blacklists. None of these email delivery companies seem to care very much about the spam they send until shit hits the fan, and now that it did it seems everyone blames the people maintaining the blacklists.
The "rate limiting" started two weeks ago, giving us a code that Microsoft's documentation doesn't even list. It remains unresolved. Never had critical issues like this on our transactional IPs prior to this, and this particular IP address is still delivering just fine to other consumer and corporate email systems.
How many users would you see as the threshold then?
Since you stated that there is a spin to this, how many users would go over your defined threshold level?
This has been affecting reputable senders who take spam reporting seriously, including MXRoute and Discourse.
> No reports probably means your reporting system is broken.
"No reports" can mean a lot of things. There is no "probably".
The "you" in "your" is Microsoft because under a certain volume of email, they don't even send reports. I regularly test the abuse contact address for my server because of this exact unfair assumption - that it must be my fault. I have never once gotten an abuse report notification from Microsoft, but I have gotten a bounce message saying that I'm blocked because I apparently send spam! Btw, this was in reply to an email from a Microsoft user.
Worse, I figured I'd just disallow any email from a Microsoft property - if an outlook (or hotmail or live or anyone else) sends an email, I can just bounce it and tell them to use a different service to reach me since I can't reply. Nope! Microsoft won't surface the bounce message to the user.
So, I am barred from replying to Microsoft emails. I am also barred from informing the sender that their email won't reach me.
It's defamation - the sender is always going to assume that it is my fault if I didn't reply even if the reason I "didn't reply" is outside of my control.
> So putting that together, it seems like a small ISP screwed up and let spammers go wild, and Outlook blocked them for it. I can't really fault Outlook for that.
Yes, in your imagined scenario, you can't really fault outlook. In the real world, however, outlook is very much to blame.
https://learn.microsoft.com/en-us/answers/questions/5786144/...
which comes from an ESP serving millions of users.
Indirect reference to this recent thread: https://news.ycombinator.com/item?id=47230704