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Network is in blocklist for hotmail mails

30-10-2014, 13:45
I went through this process quite few times on various servers.. Since I had to learn all on my own and can be quite daunting for first timers, I'll give you brief pointers so you know in what directions to move to successfully resolve this. It's generally quite easy once you grasp the basics but quite frustrating until you wrap your head around all the ins and outs.

A simple explanation first - Reasons for blacklisting
- Previous customer that held this IP may have abuse it or had email server mis-configured
- Your current mail server is mis-configured thus picked by some rigorous 3rd party mail service (*cough* brightmail)
- Countless other reasons...

- A fully working and configured email server
TIP: For first timers or ones that aren't interested in advanced DIY and all the ins and outs with it, I highly recommend following tutorials: (pick your distro and go with it)

- Make sure you have mail server configured correctly (no open relay and similar crap),
- Make sure you have a way to read the mail (may be done on CLI level as well)

First steps (figure out what's going on)
- Check your mail against major blacklists (This is a good site to start:
- If you're picked up by any blacklist, go to that site and follow the instructions (or google it) how to get unlisted

Start digging
Ignore all the "join junk or whatever services" advices you may get or find on the internet..that's useful later on but to get it working, it's completely useless not to mention it's often quite a painful process as some sites require a statement from your vendor that targeted IP belongs to you..
- Some sites will require that you met various conditions before they'll unlist you so read any output or instructions on a specific site.

Typical examples
Brightmail (hotmail's 3rd party service that's usually the cause of all the grief and pain)
Brightmail is very strict and requires all sane issues to be resolved, some of them are:
- A reverse DNS entry so it resolves to your ip
- No open relay
- SPF record (can't recall if it's requirement but is almost a rule anyway)

DNS and SPF entry
They're tied to your domain entries. You'll have to configure them right so all the issues are resolved correctly.

Domain example
Mail [MX] entry example:
Mail for zone | Mail Server | Pref
@ | | 10
* | | 10
SPF example
TXT Record
"v=spf1 a ip4:YOUR-IP/28 include:YOUR-DOMAIN include:YOUR-SUB-DOMAIN ~all"

- Google about MX zones to understand what Zones and PREFerences stand for..
-- This specific entry will mark as valid if (sub)domain is specifically stated, otherwise it will always replay as invalid source thus any mail not send from address above will probably get rejected.
-- There's a limit how much you can add in entry so google for more detailed explanation about limit as well as general FAQs

reverse DNS
This is the part where most of the beginners fail. Setting a reverse DNS entry is usually a simple process but people are often confused about how, where or what to enter.

Pretty much every VPS/Server provider has a DNS option in their panel..all you do is add entry in, which has to match your domain in MX entry and naturally IP of the server where you ran mail server, that's about it. In SYS this should be sorted in following way:
Go to your panel, select correct server (if you have many) click on IP link and then click on the icon (for appropriate IP) and then click Reverse and write in your domain name.

Once you sort all this basic steps, apply for being unlisted on any specific site, but please note that any domain changes can take up to 72h before they take affect..

Post steps
Assuming you addressed all the steps correctly you should with some luck resolve your issues but fight is far from over. Now you can apply the "join junk services" steps so you can monitor all your events and act accordingly. I wont recommend any particular way but for start you can at least add IP to your hotmail account (create if you do not have it) so you can monitor its health.

Here's the link:
All you do is sing in/register, add IP (make sure you can receive mails) and fill the details then click on the link in mail that will arrive. It will add IP to your account and you can monitor its health since hotmail is usually the biggest pain when it comes to rejecting mails..

Once you're joined you can join their junk mail program to monitor who's marking your mail as junk, your reputation and so on..but that's completely different subject.

This is by no means a full howto nor may it work for everyone, but at least if nothing else, it should give you some brief pointers about how to start addressing mail related issues. I personally use this steps for years now and all the methods applied are a sum of my years of experience in running my own stuff but naturally mileage may vary. If there's anything you wish to add or correct me, by all means feel free, I just hope it helps anyone facing mail issues.

Nate 'L0,

25-10-2014, 11:18
Quote Originally Posted by heise
Small hint. You are the ISP in the eyes of Microsoft. So contact them and follow unblocking procedures. It's really painfree and easy.
Thats quite a hint..

20-10-2014, 21:47
If you're in the Ripe database for the IPs, it is more easier, and you can sign up to the Junk Mail Reporting Partner Program.

20-10-2014, 21:32
Small hint. You are the ISP in the eyes of Microsoft. So contact them and follow unblocking procedures. It's really painfree and easy.

20-10-2014, 20:04

I have server with you, my server is at : RBX3 - Rack: 42C18 - Server ID: 162295
My ID is : jm69731-sys

Problem I am facing is hotmail is rejecting our mails, it is saying :

: host[] said: 550 SC-001
(BAY004-MC6F27) Unfortunately, messages from 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 (in reply to MAIL
FROM command)

So, it is saying that this network has bad reputation though my IP is not blacklisted anywhere. We are not involved in any kind of mass mail or promotional activities over mails. We just have few small member base , most of the mails are notification mails and members are complaining of missing notifications.

Anyone else facing similar issue ?