> Hold up, does this mean outlook sends your full credentials to Microsoft when you try to set up an outlook account?

Not just an “outlook account” - any account in outlook, with default settings at least.

I run a mail server, mainly for me but a couple of friends have accounts on there too, and a while ago one friend reported apparently being locked out and it turned out that it was due to them switching Outlook versions and it was connecting via a completely different address to those that my whitelists expected sometimes at times when they weren't even actively using Outlook. Not only were active connections due to their interactive activity being proxied, but the IMAP credentials were stored so the MS server could login to check things whenever it wanted (I assume the intended value-add there is being able to send new mail notifications on phones/desktops even when not actively using mail?).

> but this feels like it breaks all sorts of security/privacy expectations.

It most certainly does. The behaviour can be tamed somewhat, but (unless there have been recent changes) is fully enabled by default in newer Outlook variants.

The above-mentioned friend migrated his mail to some other service in a huf as I refused to open my whitelist to “any old host run by MS” and he didn't want to dig in to how to return behaviour back to the previous “local connections only, not sending credentials off elsewhere where they might be stored”.

Basically everything microsoft makes that touches http will send your username and your password to any server that asks for Basic Authentication.

It looks like Microsoft Edge had the _ability to disable_ this added in 2020 or 2021, but it isn't currently the default and the Group Policy unintuitively only applies to unencrypted HTTP Connections.

Not just that, the new outlook app makes Microsoft a complete man-in-the-middle for your email account.

https://www.xda-developers.com/privacy-implications-new-micr...

It's more common than you might think. I know of at least one popular email client that stores your credentials on their servers to enable features like multi-account sync and scheduled sending.

I think the curl -u switch just requires the password field to be filled, there obviously isn't a legit user account test@example.com with a password of password either at microsoft or at the Japanese imap server.

Most likely, and nobody cares.

Already many years ago I remember installing a firewall on my phone and noticing in surprise that Outlook was not connecting at all to my private mail server, but instead only sending my credentials to their cloud and downloading messages from there.

The only Android mail client not making random calls to cloud servers was (back then) K-9 Mail.

I think outlook is pretty much a saas product these days.

Yeah since the Windows 11 2023h2 update.

Always has been.

See replies to a similar question here (in case you haven't already): https://news.ycombinator.com/item?id=46732623

Haven't they been telling people to do that since before it became reserved? If so, the problem is more that you can't "reserve" something that's already in wide use, and mdns should've used something like .mdns.

It's like when .dev became a gTLD, knowingly breaking a bunch of setups for a mix of vanity and a cash grab. Obviously dropped the ball on the engineering side.

My company used .local for EVERYTHING. I took it as normal at the time, until I got into problems with VMWARE products.

Support patiently explained .local is reserved for something else and kindly provided Wikipedia links.

They never responded why they used .local in their docs, trainings, webinars they provided, though :)

Usage of .local for AD predated mDNS. That advice stopped with the advent of mDNS in favor of 'corp.<registered_domain>.<tld>'.

In this case, "null MX record" means MX exists, but does not specify a valid server:

   $ host -t mx example.com
   example.com mail is handled by 0 .

I'm willing to bet they were the first user to try and add example.com to their Outlook account, and MS then just assigned it to them without verifying they own the domain.

It's not really the domain but the registration in the MS Office Cloud. If you query who owns example.com mail you get that company.

Yeah, it feels more like a safety net than something you should purposefully use

I suspect they try to login and reverse engineer the IMAP config.

curl -u just requires the field to be there, I suspect. No authentication takes place. You can send any password and the output doesn't change.

It so happens that in this very specific case your obviously bad choice didn't make anything worse, that doesn't make it a good choice.

"Aha, the defective trucks only cause injuries to people who have their hands on the wheel at highway speeds, but I've never bothered holding the wheel at high speed, I just YOLO so I wouldn't be affected"

If people had used IANA's reserved TLDs they too would be unaffected because although Windows will stupidly try to talk to for example autodiscover.example that can't exist by policy and so the attempt will always fail.

As others have pointed out, using 'tmptest' works until someone buys tmptest -- unlikely, but people will buy anything these days.

I always use the ISO-3166 "user-assigned" 2-letter codes (AA, QM-QZ, XA-XZ, ZZ), with the theory being that ISO-3166 Maintenance Agency getting international consensus to move those codes back to regular country codes will take longer than the heat death of the universe, so using them for internal domains is probably safe.

It's all fun and games until Donuts buys .tmptest for some reason.

Would that really make a difference in this case? It's a configuration error / bug in Microsoft's discovery server, they could have a fallback that goes "any unknown address, return this .jp address".

.example is probably far safer than example.com.

https://www.akamai.com/blog/security/autodiscovering-the-gre...

According to it, it seems that if someone registers autodiscover.com then example.com lacking autodiscover.example.com will make Outlook try checking if autodiscover.com has an entry.

It's just a braindead system.

And then you fire off 100k emails, they all bounce, and your mail service shuts you off...

brb, just filing paperwork to apply for the .tmptest gTLD /s

Reading the article, there is a huge flaw in the autodiscover protocol by Microsoft.

https://www.akamai.com/blog/security/autodiscovering-the-gre...

According to it, it seems that if someone registers autodiscover.com then example.com lacking autodiscover.example.com will make Outlook try checking if autodiscover.com has an entry.

It's just a braindead system.