Emails blocked for emails going to outlok.com/hotmail.com

I have recently noted that my emails have been blocked when sending them to hotmail or outlook. Here is the message I get:

live-com.olc.protection.outlook.com[104.47.8.33] said: 550 5.7.1
Unfortunately, messages from [my IP] weren't sent. Please contact
your Internet service provider since part of their network is on our block
list (S3140). You can also refer your provider to
http://mail.live.com/mail/troubleshooting.aspx#errors.
[AM5EUR03FT055.eop-EUR03.prod.protection.outlook.com] (in reply to MAIL
FROM command)

I looked at the list of errors, but it is hard to know what is the issue, since my bounced mail message doe snot list an error code.
On average, we might send 1-3 email a day to varous hotmail messages, so it should not be due to spam.

Might anyone know where to look for the cause? Then, eventually, remove our IP from the list?
Thanks

 

The problem is pretty clear in the output of the log.
This is the standard behavior of email services from microsoft.
you have to contact them and apply your ip (host) to the whitelist.
You have to ensure that your mail server is setup proberly.

 

hah, good luck..
they recently put all of AWS ip's on a blacklist (30Million+ ip's straight onto a blacklist without warning or explanation), wouldn't delist any separately, even though we could show our own aws ec2 mailserver ip was good, and not spamming. took them over around 7 weeks to delist the ip's. and then they kept our ip banned, saying they'd seen a history of spamming.
how? we couldn't send ANY mail to them from that ip for 7 weeks... and i was on their smart network and junk reporting programmes.
when i looked through them, i calculated they were blocking my ip for spamming based on a total of 7 possible spam emails over an 8 month period (emails that end recipients had marked as spam, 5 of which were from mailforwards those clients had specifically requested be setup for them, delivering mail they had themselves signed up for. one recipient had twice reported a contact form email from his own website as spam. ) plus they weren't seeing any spam from the mail relay i setup on a digitalocean vps to get around their ip block.
even knowing this, microsoft support kept saying their was nothing they could do, the ip didn't qualify for mitigation.
when i pointed out i might have to take legal action, has it appears they are abusing their market position to force small competitors out of the market (after all, who's gonna use my mailservice if it's blocked from sending to millions of their customers?), they suddenly found a reason to unblock my ip.

they also have a habit of sending mail into a black hole, never to be seen or heard of again. i can trace mail being successfully accepted by their servers. yet the target recipient never receives them, not in inbox, not in spam. no rejection notice, no failure notice, no notice about breaching any policies. no notice about mail in quarantine, just hits their server and disappears without a trace...

 

ok, well for your edification and amusement:

this is their usual response:

when i asked them wtf they're on about and how did they reach that conclusion i got this from them:

which i know was absolute bullshit, since emails were fine until all of aws got blocked, and by this point, there were no more than 3 emails sent to them on this ip for over 2 months, and those ones were me testing the ip block was still active by manually sending emails with empty bodies to them from the mailserver using the cli.

so i sent them this response:

when they couldn't sufficiently explain a reason for continuing to ban our ip after that things got nasty.
microsoft's mail services really are a pain in the arse to deal with.