Look at the message headers on outlook.com and verify you are getting SPF=Pass

You could also try adding DKIM signing to your email.

Double check your droplet ip hasn't been blacklisted. Not sure if hotmail or outlook check them however. http://whatismyipaddress.com/blacklist-check does a decent job of checking most popular blacklist sites.

I have the same issue with my emails not being delivered to Yahoo email addresses.

I contacted the Yahoo's Customer Care about that and followed their procedure regarding bulk emails (even if I've never sent bulk/mass emails). They answered that the IP of my server is blacklisted.

I checked on multiple blacklist-check tools but none says that my IP is actually blacklisted.

I contacted DO's support and their answer is that there is not much we can do about that, unfortunately. In short:

The biggest issue is "the past history" of these netblocks - before we had even purchased them! We're working with mail providers to get this resolved, but in general a lot of them are slow to change in these situations. Because of this, I do not really have a quick solution for you in this case. You can try getting a new IP but there is no guarantee the issue just won't persist there.

Despite my droplet IP Not being blacklisted and getting dkim and spf working. Still no direct email to hotmail.com/outlook.com so I have found a work a round. The folks at mailgun.org have already jumped through the hoops to get email delivered to outlook & hotmail.

So just sign up for an account with them and use the wordpress mailgun plugin (to send email via their HTTP API ) or configure postfix with TLS and an appropriate transport map to submit email to mailguns - trusted-by-outlook email servers.

Yay, any news on this?
I don't want big corporations to snoop on my email... is it possible to detect the destination email domain, and use an external provider when I detect mail for outlook, hotmail or yahoo?

Any news? I'm in the same situation. Configured SPF records, dkim keys and only problems with hotmail, live or outlook accounts. My ip is not blacklisted, but doesn't send enough mails to have any reputation and when talk to outlook support, they returned: "ip not qualified for mitigation"
Any suggestion? usually change ip of droplet works? Big corporations with nonsense politics are really a pain...

Any solution like this, relay mails to hotmail with an smpt service like mailgun or similar?
Relay host based on destination MX record:
http://serverfault.com/questions/663418/relay-host-based-on-destination-mx-record

I got the same problem. My droplet is in the AMS3 datacenter, my IP starts with 178.62.226.xxx

I changed my postfix config to send mail to hotmail, live, msn and such via GMAIL with authentication/TLS. It's working now but ...

Caveats:

• The sender address gets changed to my GMAIL address wich i rather not have
• I had to lower my security settings on GMAIL account
• Via the CAPTCHA UNLOCK I had to trigger the allowance of my postfix connecting to GMAIL SMTP with auth/TLS.

Interestingly enough a mailbox (@msn.com) that had a long time ago once received e-mail from this from address (back on other hosting) worked every single time. All other hotmail (etc.) mailboxes that had never received an e-mail from this sender address got bounced with the mailbox unavailable

I'm facing the same issue. It's quite ridiculous really. I've done various blacklist checks and I'm on none.

Just working my way through this article to solve it:
https://www.rackaid.com/blog/hotmail-blacklist-removal/

This form looks like it may go somewhere but you never know with Microsoft, king of unexpected waiting times:
https://support.microsoft.com/en-us/getsupport?oaspworkflow=start_1.0.0.0&wfname=capsub&productkey=edfsmsbl3&locale=en-us&ccsid=635992556112449734

I'm having lots of fun with this at the moment... I've set up SPF, DKIM, altered the servers FQDN to reflect the domain I am sending mail for and I get the following error from Outlook/Hotmail

Jun 28 10:13:21 main postfix/smtp[28083]: AE01C62D00: to=ADDRESS@hotmail.com, relay=mx2.hotmail.com[65.55.92.136]:25, delay=0.56, delays=0.09/0/0.35/0.11, dsn=5.0.0, status=bounced (host mx2.hotmail.com[65.55.92.136] said: 550 SC-001 (SNT004-MC1F26) Unfortunately, messages from X.X.X.X weren't sent. Please contact your Internet service provider since part of their network is on our block list. You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. (in reply to MAIL FROM command))

Filled in the form ( https://support.microsoft.com/en-us/getsupport?oaspworkflow=start_1.0.0.0&wfname=capsub&productkey=edfsmsbl3&locale=en-us&ccsid=635992556112449734 ) and I just got the following response

Note: Errors are unlikely, however, if an error is indicated, please resubmit the specific IP or IP range.

I've just resubmitted, but I expect I will get exactly the same back again. I've never had much luck with Microsoft / Email. I have Office 365 and for about 2 weeks I couldn't actually send out any emails (even from their Outlook web interface). Their response was to ask me to send emails to them from the offending domain... which I couldn't because it didn't work.

Ohhh goody, I have actually had another response

Note: Errors are unlikely, however, if an error is indicated, please resubmit the specific IP or IP range.

I'm having a hard time as well. New emails are not bounced, nor do I get an error message in my mail log. Funny thing is, replying to an email sent from a hotmail account DOES work.
So I had a look at the differences in headers. The only field was:

in-reply-to: <AMSPR05MB1163A06679EE051280F0EF78EE20@AMSPR05MB116.eurprd05.prod.outlook.com>

This resulted in the following DMARC report:

<policy_published>
<domain>engeen.nl</domain>
<adkim>r</adkim>
<aspf>r</aspf>
<p>none</p>
<sp>none</sp>
<pct>100</pct>
</policy_published>
<record>
<row>
<source_ip>188.166.43.30</source_ip>
<count>3</count>
<policy_evaluated>
<disposition>none</disposition>
<dkim>pass</dkim>
<spf>pass</spf>
</policy_evaluated>
</row>
<identifiers>
<header_from>engeen.nl</header_from>
</identifiers>
<auth_results>
<spf>
<domain>engeen.nl</domain>
<result>pass</result>
</spf>
<dkim>
<domain>engeen.nl</domain>
<result>pass</result>
</dkim>
</auth_results>
</record>

I have no idea what do try next...
Does anyone know of an affordable relay as an alternative?

I've been fighting to get Hotmail to accept our emails for a long time. We go through this process with pretty much every new website or IP address. We have a brand new IP address and server from DigitalOcean, but apparently Microsoft doesn't really give you anyway to reset the history of an IP address. But you might as well try these things:

• JMRP and SNDS: Sign up to get hotmail spam reports https://postmaster.live.com/snds/addnetwork.aspx
• https://support.microsoft.com/en-us/getsupport?oaspworkflow=start_1.0.0.0&wfname=capsub&productkey=edfsmsbl3&ccsid=635688189955348624&wa=wsignin1 - They'll always just tell you your IP is "not qualified for mitigation". Just keep on replying to their emails and ask them to do something to help you. If nothing happens, fill out the form again every couple of weeks and try again.
• Email delist@messaging.microsoft.com
• Fill out the form at https://sender.office.com
• Try calling Microsoft at 800-865-9408. I didn't have any luck with that, but some people say they have.
• Post multiple messages in https://answers.microsoft.com/en-us/outlook_com/forum?tab=Threads. Some Microsoft employees do sometimes read those messages and every now and then you'll get someone who can help. But you have to be persistent and continue posting new threads every few days.
• Ask people who use your website not to use @outlook.com or @hotmail.com email addresses and tell them why.
• Send an email from a Hotmail account to your blocked email address. And also reply from your blocked email address. You should at least get the reply. Check it in Hotmail (view source) for any issues that appear in the headers.

Just keep on repeating those steps every few weeks. Good luck.

I found this in the microsoft support forum.
The page looks very similar to the sender.office.com page linked above, but requests many more fields. Perhaps this is the updated version of the same service.
https://support.microsoft.com/en-us/getsupport?oaspworkflow=start_1.0.0.0&wfname=capsub&productkey=edfsmsbl3&locale=en-us&ccsid=635639051175184163