outlook.com and O365 are horrible to deliver to. We regularly get issues where we sent an email it was accepted by O365 but was never delivered to the mailbox. We have one person working at least half the time on resolving stuff like that. And that's from a respectably maintained SES egress with good reputation, DMARC, DKIM configured.

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drdaeman 3 hours ago | parent | next [-]

There is a trick. Sign up with them, configure custom domain, but don’t set your MX records. On your MTA, route mail that goes to Outlook/Hotmail to go through their MSA with your Outlook credentials and headers stripped as if submitted directly by user. Outlook gets mail through their own MSA it trusts, rest of the world talks to your mail system directly. Replies still go to your MXes.

I haven’t productionized this setup (I send maybe a dozen emails a year) but it worked for me ad hoc a couple years back, when I had to send a mail to an Outlook-hosted address and they blackholed everything I tried to send while 250 OKing me.

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lakeviewterrace 3 hours ago | parent | prev [-]

Funny, they have no problem handling mail for essentially every Fortune 500 company and others large and small.

It's always people self-hosting mail on a shared server in Moldova (because they think it makes them cool) that are complaining.

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pembrook 2 hours ago | parent | next [-]

Self hosting mail on a shared server in Moldova is basically the entire idea behind email (and the internet).

Which with cheap models like Jev as spam classifiers, this can now become a reality.

The problem is, Google and Microsoft have monopolized the entire email market, so their esoteric deliverability mysticism from 2007 still persists (basically blanket bans on entire IP spaces, locking out anybody trying to send emails on their own).

	▲	lakeviewterrace 2 hours ago \| parent [-]
		People used to have party lines and leave their doors unlocked too, but it turns out the world is filled with bad actors and other assorted shitty people. Email naturally followed this evolution.

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pacija 3 hours ago | parent | prev [-]

Nope, people self-hosting mail on their own hardware from their own basement in Serbia ;)

https://www.mimar.rs/blog/a-journey-of-my-mx-server-to-new-r...

And yes, it's cool not to have to let scum read your private communications :D