IMPORTANT: Is Microsoft or Cloudmark blocking your email? @hotmail/@live/@msn/@outlook email addresses

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Albert Wiersch
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IMPORTANT: Is Microsoft or Cloudmark blocking your email? @hotmail/@live/@msn/@outlook email addresses

Post by Albert Wiersch »

Is your email being blocked by Cloudmark?

Cloudmark may be blocking your legitimate email as this service has blocked several emails from us.

Examples of Cloudmark blocked email

Code: Select all

<your email address>: host mx1.hostinger.com[172.65.182.103] said:
    554 5.7.1 Sender IP Blocked by CSI. For remediation please use
    https://csi.cloudmark.com/en/reset/?ip=50.116.31.253 (in reply to RCPT TO
    command)
Is your email being blocked by Microsoft?

If you have a hotmail.com, live.com, msn.com, outlook.com, or other Microsoft controlled email address (like yourname123@outlook.com or yourname123@live.com, etc.) (or you are using a Microsoft email service) and you are not getting email from us then please note that Microsoft has a history of indiscriminately blocking legitimate email servers and may be blocking email from our primary email server at IP address 50.116.31.253 (as well as email from other legitimate mail servers).

Your blocked email will not even show up in any spam or junk folders because it is simply rejected and sent back to us.

We have notified Microsoft of this problem numerous times (including multiple emails to delist@messaging.microsoft.com) but our requests to fix it have so far been ignored and/or rejected and/or blocked or have generated a useless response. At other times Microsoft will claim to have unblocked our IP, but it continues to be blocked (or is unblocked only temporarily). So please note we have done everything reasonable to notify them of this problem and it's out of our hands at this point. However, we will continue to search for a solution and continue to report this Microsoft in hopes for an eventual resolution.

Note that this email blocking problem may also affect you if your email provider or service also uses the affected Microsoft and/or Outlook blocking mechanism (or Microsoft SMTP server) even if you don't have a hotmail.com, live.com, msn.com, or outlook.com email address. Note also that this problem may also block legitimate email to you from other servers (and not just from our server).

Examples of Microsoft blocked email

Code: Select all

<XXX@outlook.com>: host
    outlook-com.olc.protection.outlook.com[52.101.41.5] said: 550 5.7.1
    Unfortunately, messages from [50.116.31.253] 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.
    [SJ5PEPF000001D2.namprd05.prod.outlook.com 2024-06-05T13:57:43.973Z
    08DC7F597EF12787] (in reply to MAIL FROM command)

Code: Select all

<xxx@msn.com>: host msn-com.olc.protection.outlook.com[104.47.51.225] said:
    550 5.7.1 Unfortunately, messages from [50.116.31.253] 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.
    [AM7EUR03FT025.eop-EUR03.prod.protection.outlook.com
    2024-01-09T16:49:28.177Z 08DC112C4D6B06F7] (in reply to MAIL FROM command)

Code: Select all

<xxx@tbs-sct.gc.ca>: host
    tbssct-gc-ca0i.mail.protection.outlook.com[104.47.75.164] said: 550 5.4.1
    Recipient address rejected: Access denied. AS(201806281)
    [YT3CAN01FT017.eop-CAN01.prod.protection.outlook.com
    2024-01-09T16:49:24.404Z 08DC10E9B64AA284] (in reply to RCPT TO command)

Code: Select all

<xxx@live.co.uk>: host eur.olc.protection.outlook.com[104.47.18.97] said:
    550 5.7.1 Unfortunately, messages from [50.116.31.253] 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.
    [AM6EUR05FT008.eop-eur05.prod.protection.outlook.com
    2023-04-01T20:36:42.954Z 08DB32C74FFE8043] (in reply to MAIL FROM command)

Code: Select all

<xxx@hotmail.com>: host
    hotmail-com.olc.protection.outlook.com[104.47.57.161] said: 550 5.7.1
    Unfortunately, messages from [50.116.31.253] 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.
    [DM6NAM11FT086.eop-nam11.prod.protection.outlook.com
    2024-01-09T16:49:19.916Z 08DC1104793D994E] (in reply to MAIL FROM command)

Code: Select all

<xxx@outlook.com>: host
    outlook-com.olc.protection.outlook.com[104.47.56.33] said: 550 5.7.1
    Unfortunately, messages from [50.116.31.253] weren't sent. Please contact
    your Internet service provider since part of their network is on our block
    list (S3150). You can also refer your provider to
    http://mail.live.com/mail/troubleshooting.aspx#errors.
    [DM3NAM02FT049.eop-nam02.prod.protection.outlook.com] (in reply to MAIL
    FROM command)

Code: Select all

<xxx@xxx.gov.uk>: host
    xxx.mail.protection.outlook.com[104.47.5.36] said: 550
    5.7.511 Access denied, banned sender[50.116.31.253]. To request removal
    from this list please forward this message to
    delist@messaging.microsoft.com. For more information please go to
    http://go.microsoft.com/fwlink/?LinkId=526653. AS(1410)
    [HE1EUR02FT056.eop-EUR02.prod.protection.outlook.com] (in reply to RCPT TO
    command)
Microsoft says to contact our Internet service provider but that is useless. It is Microsoft who is blocking the email, not our service provider (Linode). However, our provider is also a victim of this and is also trying to get Microsoft to fix their email blocking problem (with limited success as of now).

What about other email?

There is a reasonably good chance that your email from some other legitimate sources/servers could also be blocked. Please be aware of this potential issue until Microsoft fixes this problem. Our research indicates that there are other legitimate mail servers which have also suddenly been blocked for no apparent reason (evidence here).

What can you do?

If our email to your email address is being blocked then please email us at support at htmlvalidator dot com with a properly working email address (like Gmail) and we will respond to that email address.

(RECOMMENDED) You can also change your email address in our system using the forms here (use the first form if you know your registration number number and PIN number):
https://www.htmlvalidator.com/support/u ... l-form.php

Then you can have your registration information sent to the updated email address here:
https://www.htmlvalidator.com/sendkey.php

If you have a forum account here then you can send me a private message through the forum, but you may not be able to receive any email messages or notifications of new messages from the forum if I reply to your message, so you'll need to remember to check back here for new replies.

If you don't have a forum account then you can sign up for one. Because your confirmation email from the forum may be blocked, you'll need to send me an email with your forum username so I can activate your forum account manually. After I activate your forum account then you should be able to send me a private message through the forum, and receive a reply back through the forum.

Another option would be to message us through Facebook:
https://www.facebook.com/htmlvalidator

If you're able to report this problem to Cloudmark or Microsoft, then please do so. We hope you'll get a better response than we've been getting.

Use or switch to a Gmail account

Gmail usually has the least problems and best spam filtering, but legitimate email can sometimes still end up in a spam folder, so please check your spam folder if you are expecting any email or license keys from us.

Fortunately we've never run into a problem with Gmail where Gmail completely blocks all our email and returns it to us (although sometimes it might end up in your spam folder).

Update 2022-01-25

Good news. It appears that the Microsoft email block on our primary email server has been lifted (for now) but we are leaving this notice up because these Microsoft email blocks can come and go for seemingly no reason. Also, other legitimate email servers still seem to be blocked (based on reports on the Internet), so Microsoft may still be blocking legitimate email from other sources.

Update 2023-03-29

It looks like this problem has suddenly returned, at least for some users. Again we recommend that you upgrade to a Gmail account if possible, or at least have a backup Gmail account that you can use when needed.

Update 2024-01-09, 2024-06-05

It looks like this problem has returned yet again, at least for some users. Again we recommend that you upgrade to a Gmail account if possible, or at least have a backup Gmail account that you can use when needed.

Update 2024-11-10

Added information about Cloudmark also blocking legitimate email.
Albert Wiersch, CSS HTML Validator Developer • Download CSS HTML Validator FREE Trial
User avatar
Albert Wiersch
Site Admin
Posts: 3821
Joined: Sat Dec 11, 2004 9:23 am
Location: Near Dallas, TX
Contact:

Re: IMPORTANT: Is Microsoft blocking your email? @hotmail/@live/@msn/@outlook email addresses

Post by Albert Wiersch »

Unfortunately it seems this is happening again. Our mail server is blocked, then unblocked, then blocked again, for who knows what reason(s). So please use a gmail (or other working email account) if possible. Thank you!
Albert Wiersch, CSS HTML Validator Developer • Download CSS HTML Validator FREE Trial
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