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May be related but I'm not sure. Fastmail seems like a well-known company and I think their servers would be on reputable sender lists. In that sense MXRoute was explicit about their insistence on keeping their servers trusted and that they would come down hard on users that would compromise their reputation.

When a message to Hotmail is delayed or blocked, I get an email from Fastmail containing details from Microsoft including the IP address of the offending server. When I look that address up in blocklists, the results are clean: No blocks amongst 60+ lists tested (depending on the service).

It feels like MS is checking the current SMTP address for my domain against the prior Rackspace address. It's as if it trusts the old server IPs and something needs to happen to have the new SMTP IP address(es) get trusted. But, none of the links that MS puts into its bounce messages say explicitly what to do. I've sent a lot of mail to Hotmail-having family in the past and they went through most of the time. Not perfect but close. One message even went through today after two got blocked.

I tried delisting the claimed offending IP address in the bounce message using an Office365 tool. Noticed in the confirmation message that Hotmail/Outlook.com delisting was handled through a separate link and have filed a ticket there.
 
My wife has said that she often gets an "invalid email address" error when entering her Fastmail address on several different websites requiring an email address to access the features of the website.

Most people don't realize that your email address is checked in real time when you are entering it on many websites. (Edited to add: especially when creating accounts)

Essentially, the website opens up an email transaction with the email domain and username given, and if the result for opening up that transaction comes back with an error, the website assumes the email address isn't valid.

To be clear, it's not sending an email... just performing the first part of the email process and if the first part doesn't work, the assumption is that it's a fake email address.

Now, the error could be anything, and it could just be that fastmail is on a blacklist, or that the website is not processing what hotmail sends back correctly, or that hotmail is onto this game and just isn't participating.
 
The Hotmail/Outlook.com problem continues. Some go through, some get retries, others get rejected with the S3150 fatal error. No answer yet from Fastmail's Tier 2 support. I'm pretty pleased with the rest of the Fastmail service but this is very troubling. Any other Fastmail users having or had delivery problems to MS?
 
The Hotmail/Outlook.com problem continues. Some go through, some get retries, others get rejected with the S3150 fatal error. No answer yet from Fastmail's Tier 2 support. I'm pretty pleased with the rest of the Fastmail service but this is very troubling. Any other Fastmail users having or had delivery problems to MS?
Microsoft has a massive outage today. It isn't FastMail.

 
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Interesting, thanks. The MS sites I've been looking at re: my delivery problems differentiate between Microsoft 365 and their Hotmail.com/Outlook.com products (different ticketing sites for each.) But, it does seem possible that this could be part of my problem.

/Airplane!
I picked a bad week to migrate.
/Airplane!
 
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Interesting, thanks. The MS sites I've been looking at re: my delivery problems differentiate between Microsoft 365 and their Hotmail.com/Outlook.com products (different ticketing sites for each.) But, it does seem possible that this could be part of my problem.

/Airplane!
I picked a bad week to migrate.
/Airplane!
It hit our work and the college that my wife works at too - lol.

Microsoft is aware of it. Looks like you were not the only one: https://forums.macrumors.com/thread...nloading-emails-from-exchange-server.2476451/ lol
 
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Yikes. If Stanford's affected (#3 on the linked thread) it should get some eyes on it! I was a grad student there some decades ago, a little before the Yahoo and Google guys changed the admissions game. Back then we sent email from Unix terminals and with the -v flag, watched the connection being made, the message sent, and the link closed.

/Monty
But we were 'appy in those days...
/Python
 
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Fastmail has updated me a couple of times on the MS problem. They're working on it as it has affected other customers. https://fastmailstatus.com/

It may take some time for everything to shake out but for the past couple of days I've been able to send to hotmail.com without throttling or bounces.

Overall, I'm happy with the switch and have cancelled Rackspace hosting.

Thanks again to everyone for the advice and pointers.
 
As the linked article says, "This is for techies and sysadmins" and "this will not be easy and I don’t recommend you do it unless you WANT to learn a ton of stuff.." I did learn a lot from the article but the big lesson is that I am an email consumer. I need it to work and a few bucks a month to a provider is a good exchange for me.
 
As the linked article says, "This is for techies and sysadmins" and "this will not be easy and I don’t recommend you do it unless you WANT to learn a ton of stuff.." I did learn a lot from the article but the big lesson is that I am an email consumer. I need it to work and a few bucks a month to a provider is a good exchange for me.
Running/maintaining your own email server is a fools errand. The only case it makes sense is if you are getting paid to do it.

Its very much worth paying less than the cost of a latte per month for that burden to be on someone else.

Especially if you care that you get successful delivery of and receive all mail.
 
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Running/maintaining your own email server is a fools errand. The only case it makes sense is if you are getting paid to do it.

Its very much worth paying less than the cost of a latte per month for that burden to be on someone else.

Especially if you care that you get successful delivery of and receive all mail.
The time for running/maintaining your own email server passed 20 or so years ago. A lot of providers will drop any email not coming from a whitelisted sending host.
 
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