Postfix mail server not delivering to hotmail.

March 6, 2017 162 views
Email Ubuntu 16.04

I have a server that I'm using to send mail via postfix. It's delivering to other major providers like gmail and icloud, but it's not sending to any of microsoft's domains.

A bit of background, I initially didn't realise I needed to do anymore work after installing postfix, so I was sending messages without any authentication, after a couple of days they stopped reaching my personal hotmail account.

I've since sorted out the SPF, DKIM, DMARC and PTR records so that it's a much more legit operation, but alas, nothing is reaching my hotmail account.

If you need more information to diagnose the problem, please let me know and I'll provide.

4 Answers


One of the first things I'd recommend would be a scan on your IP and Domain against blacklists. This will let you know if blacklists are the issue.


  • My domain is OK with nearly all of them, save a few that timeout at the end.

    • What is the response from Hotmail's servers in the logs? /var/log/mail.log

Hotmail is pretty picky about how fast you send transactions. As @hansen said, the mail log should give you the reason that mail cannot be delivered and from there we could provide some help in addressing the problem.

The same is happening to me.

My startup's email server is hosted on DigitalOcean. For an unknown reason it does not deliver emails to any of Microsoft's services (Hotmail, Live, Outlook).

I've been running it for two years, it only sends legit personal emails, not even "drip campaigns" or such.

Their mx reports that the mail has been delivered, but it does not appear in the recipient's inbox or spam folder. It is simply lost and I can't even monitor delivery errors. Sometimes a message goes through (usually a direct reply to an incoming mail) but that's not even guaranteed. There are no errors in postfix. The message is reported as delivered.

I've completed all checklists, my mailserver uses DKIM, SPF, in-transit TLS, does not send spam, has a reverse PTR, etc, etc. The IP is not listed in any blacklist. I get a perfect 10/10 score in most mail tester services.

Other MXs like Gmail and Yahoo! deliver emails properly, sometimes to the spam folder but that is usually fixed when the recipient clicks on "Not spam".

Contacting their support is talking to a wall. It's impossible to get a non-canned response.
Short of paying the extortion fee for a "deliverability certificate" I honestly don't know what else to do. I understand spam is a serious issue but come on, how are small businesses supposed to send emails if they don't want a third party like Google Apps to read them?

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