Can't send mail to Microsoft accounts.

Is the Linode address space on a black list somewhere?

My Linode host is configured as a mail server with iRedMail. I am blocked sending to Microsoft accounts (i.e. Hotmail, Outlook).

For Hotmail I get the following:

Jan 27 12:47:09 mail postfix/smtp[4553]: 22C671E47D: to=<[email protected]>, relay=mx1.hotmail.com[65.55.92.152]:25], delay=0.44, delays=0.01/0.03/0.37/0.04, dsn=5.0.0, status=bounced (host mx1.hotmail.com[65.55.92.152] said: 550 SC-001 (SNT004-MC2F7) Unfortunately, messages from 45.33.81.137 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)),</[email protected]> 

The error they reference: 550 SC-001, states:

"Mail rejected by Outlook.com for policy reasons. Reasons for rejection may be related to content with spam-like characteristics or IP/domain reputation. If you are not an email/network admin please contact your Email/Internet Service Provider for help"

The mail is not "spam-like" so it must be the reputation of the IP/domain.

For Outlook I get:

Jan 27 12:47:51 mail postfix/smtp[4553]: D81AF1E47D: to=<[email protected]>, relay=schreblerlaw-com.mail.protection.outlook.com[207.46.163.170]:25], delay=6.3, delays=0.01/0/0.62/5.6, dsn=5.7.1, status=bounced (host mail.protection.outlook.com[207.46.163.170] said: 550 5.7.1 Service unavailable; Client host [45.33.81.137] blocked using FBLW15; To request removal from this list please forward this message to [email protected] (in reply to RCPT TO command))</[email protected]> 

I've requested delisting but have heard nothing back.

Any ideas?

12 Replies

Please refer to the thread below for learning about mail ejection by Microsoft Outlook -

http://answers.microsoft.com/en-us/outl … ed9a0?db=5">http://answers.microsoft.com/en-us/outlook_com/forum/oemail-osend/mail-rejected-by-outlook-for-policy-reasons-550-sc/561a2bcf-deb6-4e6b-89ef-49af350ed9a0?db=5

Also, check your ip and see if any of your neighbors have a bad reputation.

https://talosintelligence.com/reputation_center/lookup?search=YOUR_IP

I belive Linode may be allowing bad players to pollute the email reputation of a block of ip's. (don't know for sure). Have asked support about this and nothing so far.

Yes. Linode is on UCEPROTECT Level 3 blacklist (ASN 63949) due to an extremely high spam score for the ASN. Not sure if this means all Linode IP's or not, but certainly mine is on the block list, simply because some of my neighbors have been naughty.

My specific IP, and the subnet it is on, come up clean on every blacklist I have checked, and I have all the currently proper authentication and verification measures successfully in-place and passing (i.e. DKIM, SPF, DMARC, PTR, MX and so forth).

I have tickets open with both Microsoft and Linode, however have not heard anything as of yet.

Apparently, since my rep is clean (not on Level 1), I am allowed to pay whitelisted.org (who runs UCEPROTECT) to have my IP specifically removed from the blacklist for the equivalent of about $30 per month or $60 for six months, etc.-- although it is unclear as to whether this will alleviate the block from Outlook.com's servers.

Personally, I feel this is extortion, as I have done nothing wrong and my server has never been compromised, nor sent out spam or even mailing lists of any sort.

All I did was everything right, except had some shady folks move into the neighborhood.

I understand they need to make money too, but none of this was my fault, nor my choice. Just a victim of circumstance, like yourself.

Hopefully this will be resolved soon.

Hi. Thanks. Went through the process of manually de-listing with Outlook.com for individual IP block as recommended in the first set of bounces, then contacted Linode Support as recommended in the bounces afterward. Tested send/receive OK with Outlook.com address, no more bounces.

Note: I had all the recommended security checks successfully in-place before-hand, namely SPF, DKIM, DMARC, and PTR. If you don't have these, you will want to implement them first. Also, be sure to clear up any other black-list issues, if you can. This was part of the reason MS was so quick to unblock me, since I've had all those checks in-place and have had a clean record regarding both my server and it's IP.

@jdmayfield writes:

This was part of the reason MS was so quick to unblock me, since I've had all those checks in-place and have had a clean record regarding both my server and it's IP.

I would say that you got very, very lucky. M$ could have just ignored you or told you to take a hike. IMHO, those two outcomes are much more frequent than the one you received.

-- sw

Hi, stevewi.

Not just luck. MS doesn't want to block legitimate senders. That's bad for business. What I did was fulfill all of the requirements, had no history of spamming, a fairly long history with my server's IP (~5 years), and followed their requested processes, which included reaching out for help from my ISP (Linode). This last step was specified clearly in the bounce messages.

Probably doesn't hurt that I've helped Outlook a couple of times with their own deliverability issues (i.e. mismatched DKIM keys I discovered a few years ago, causing their mail to be rejected or quarantined by servers world-wide).

Yes, they could ignore me. But this isn't my first rodeo. I do this kind of thing at my day-job all the time. I'm a Network Administrator for a small-town ISP and computer shop. I personally handle the mail-servers at work as well, and have dealt with this issue before.

Sometimes the squeaky wheel really does get the grease.

"Not just luck. MS doesn't want to block legitimate senders. That's bad for business."

Well they are blocking us without any explanation. Pure extortion.
SPF, DKIM, DMARC all set. We're not blocked anywhere. Still we can't deliver email to our core business partners since they are using "*mail.protection.outlook.com".

Very professional.
We will probably move away from linode to a custom dedicated email provider. We're losing flexibility and good service but we're forced to do it.

I just want to say few words about this issues.

I am using Linode for more then 8 years and nevere had any problems with IP's blocking or black listed from MS.

In last 4 days we had a HELL in our business just because of idiotic black lists from Outlook-MS.

We've done everything what they said about notifications in emails.
Even we had contact them on official Twitter account.
So out business is crippled because of it and no body cares, we don't even use this shit of Office 365 and Outlook, but I just wondering why the hell we are waiting almost two days on answers from Linode support ?

This experience was totally frustrating for us and for our clients.
So after 8 years first time I am thinking to remove completely my business from Linode to another provider.

There is no excuses for blocking IP's without reason, because we had all protections, all antispam , antimalware etc.. software's on our side, so why they blocked our IP ???

No, never we gona use this any of degeneric MS products, we gona change our business but we not gona use any of MS, never-ever!

In last 4 days we had a HELL in our business just because of idiotic black lists from Outlook-MS.

Why didn't you simply sign up with some web-host/mail ISP like pair.com or bluehost.com etc., and direct all mail through there via a MX DNS record at the registry or nameserver level?

That might have taken four or five hours to propagate and the disruption would have been minimal.

That is what we do. We don't run our own mail servers. The cost is the same to run a Linode $5/mo mail server (i.e. Mail-In-A-Box https://mailinabox.email/)for a small shared server from an ISP just for mail.

@acanton77

Well we've done something similar with new domain and new share hosting.
But I just feel disappointed after all this years.

That might have taken four or five hours to propagate and the disruption would have been minimal.

We thought that delisting will be done as they said in maximum 24 hours, but it takes more then 72. So can't explain our level of frustration in that period.
Anyway thank you for share this about Mail-in-a-Box.
I will check for sure.

@acanton77
Hello. Could you please explain a bit more how you do this mailinabox+emailserver provider?
How do you switch from standalone mail server on linode to that setup? How do you move existing imap emails? What if there's 300GB of emails?

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