Why can't I email Hotmail addresses from our company email addresses?

Question

I have been receiving the following error message when trying to email hotmail addresses.

Reporting-MTA: dns; xxxxx.com
X-Postfix-Queue-ID: 3CD3C600B9
X-Postfix-Sender: rfc822; [email protected]
Arrival-Date: Mon,  1 Oct 2018 09:21:25 +0100 (BST)

Final-Recipient: rfc822; [email protected]
Original-Recipient: rfc822;[email protected]
Action: failed
Status: 5.7.1
Remote-MTA: dns; hotmail-com.olc.protection.outlook.com
Diagnostic-Code: smtp; 550 5.7.1 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 (S3140). You can also refer your
    provider to http://mail.live.com/mail/troubleshooting.aspx#errors.
    [VE1EUR02FT053.eop-EUR02.prod.protection.outlook.com]

I initially contacted the company who provides us with he email server and domain name, and was told all was healthy.

We can email other email addresses such as gmail, sky, bt etc.

On googling snippets of the above, and the error codes it led me to believe I was on a block list.

I checked to see if your mail server's IP or domain name was on any kind of blacklist using the following websites:

https://www.spamhaus.org https://mxtoolbox.com

It does not appear that we are on a blacklist.

I then proceeded to fill in a request on the microsoft support website: https://support.microsoft.com/en-us/supportrequestform/8ad563e3-288e-2a61-8122-3ba03d6b8d75 I found this through a troubleshooting guide.

I got a response a couple of days later saying that they needed more information (I'm not sure what else to provide apart from the above, althought I did not X out the IP and names) and nothing seems wrong with the IP Range provided.

Getting chewed out no end because we can't email hotmail and am totally out of rational options.

May convert and start praying at this point.

-- update --

I have got a reply from Outlook.com Deliverability Support

We were unable to identify anything on our side that would prevent your mail from reaching Outlook.com customers.

On their recommendation I signed up for Smart Network Data Services program (SNDS) http://postmaster.live.com/snds/. Although, I am not entirely sure what it is, and if it would help.

I have replied requesting support, and enclosed the error message here.

Currently waiting out for Outlook Support to get back to me.

-- update --

Response from Outlook Team:

` Hello,

My name is xxxxxx and I work with the Outlook.com Deliverability Support Team.

Recent activity coming from your IP (x.x.x.x) has been flagged by our system as suspicious, causing your IP to become blocked. I have conducted an investigation into the emails originating from your IP space and have implemented mitigation for your deliverability problem. This process may take 24 - 48 hours to replicate completely throughout our system. `

Will check back in a couple of days with the result.

Answer 1

The email headers clearly show that your mail server's IP (or your ISP provider's IP) is blacklisted. (Here, whatever is i [x.x.x.x] is blacklisted by Microsoft). Since you have already contacted Microsoft and got the response from them, you just need to proceed further and reply them with the following details:

1) Your mail server's IP address is not blacklisted in any of the RBLs. Give some proofs as well such as https://www.spamhaus.org, https://mxtoolbox.com with the links which show your IP address reputation is good.

2) Also, reply to them with the actions you have taken to secure your mail server and there are no chances of spamming from your servers.

3) Along with that, you may also need to convince them that the emails you send are for just business/personal purpose and they are not meant to spam anyone.

Also, it would be a good idea if you can ask them the reason for the blacklist so that you can take necessary actions in the future.

Generally, it takes up to 48 hours and your IP address should get whitelisted.

Answer 2

The bounce message tells you the problem - the sending IP is in a blocked list. Without knowing the IP address its no possible to advise more specifically, but either you are using a range marked by your provider as not suitable for SMTP servers, or there has been spam from that IP before or there is a misconfiguration - In any event, this is not something you can fix without changing your IP address or getting help from your ISP.

Additional Information to address your comment question

(Simplifying a bit) Every Internet connection has an IP address which uniquely identifies the computers associated with it. The IP address of your computer (router actually) is assigned by your ISP, and is part of a block of IP addresses which they control.

It is possible for another provider to get a good indication of which ISP those addresses are associated with. In addition, there are lists of IP ranges allocated by ISP's as being customer/dynamic IP's, and these IP address ranges can be checked by email servers, and email rejected as likely spam. (See information about the PBL Blocklist here)

The problem seems very much like Hotmail has identified the address you are sending email from as "not reputable" (good luck finding out why from them) - quite possibly because its n the PBL or another similar list.