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We send daily mass emails to our customers (~30,000+ emails per day). We have problems with Hotmail users receiving our emails. Sometimes the email goes to the Junk folder, but often it will got to their inbox, but the content is blocked so the user sees a message saying "This email was blocked and may be dangerous". If an email is sent to GMAIL it is usually not blocked, but it does show up as from "Uknown" instead of the company.

Please be advised I've done the following: 1. No RBLs Checked on -> http://multirbl.valli.org/ 2. We do have SPF records published 3. We do have reverse DNS setup 4. Our company even signed up for the Junk Mail Reports Program at Hotmail

Here is a sample header, I've noticed the X-SID-Result and the X-AUTH-Result both FAIL every time at Hotmail:

X-Message-Delivery: Vj0xLjE7dXM9MDtsPTA7YT0wO0Q9MTtTQ0w9MQ==
X-Message-Status: n:0
X-SID-Result: Fail
X-Message-Info: JGTYoYF78jFqAaC29fBlDlD/ZI36+S6WoFmkQN10UxWFe1xLHhP+rDthGRZM87uHYM926hUBS+s0q46Yx9y6jdurhN6fx0bK
Received: from privatecompany.com ([WanIPAddress]) by col0-mc3-f30.Col0.hotmail.com with Microsoft SMTPSVC(6.0.3790.4675);
     Wed, 5 May 2010 08:41:27 -0700
X-AuditID: ac10fe93-000013bc00000534-46-4be191a1618e 
Received: from INTERNAL-Email-SERVER([InternalIPAddress]) by privatecompany.com with Microsoft SMTPSVC(6.0.3790.4675);
     Wed, 5 May 2010 11:41:21 -0400
From: Private Company, Inc.<EmployeeUsername@privatecompany.com>
To: PrivateClient@hotmail.com
Message-Id: <20100505114246.658849984@privatecompany.com>
Date: Wed, 5 May 2010 11:42:46 -0400
MIME-Version: 1.0
Reply-To: EmployeeUsername@privatecompany.com
Content-Type: text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding: 8bit
X-Brightmail-Tracker: AAAAAA==
Return-Path: bounce@privatecompany.com
X-OriginalArrivalTime: 05 May 2010 15:41:27.0837 (UTC) FILETIME=[6D06E4D0:01CAEC69]

marked as duplicate by Jenny D, dawud, peterh, HBruijn, masegaloeh Jun 16 '15 at 8:26

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.


The solution I found for Hotmail to quit blocking the content of the email was in the configuration of the mass email formats; this also fixed the problem of gmail recipients seeing our emails as "Uknown Sender".

Examples: Our emails were original sent as "Mr. President " and this would cause hotmail to block the content and for gmail to mark us as unknown sender. However if you get the display name to match the email address it is delivered okay.

It has to be EXACT though; here are some examples -

Good: Mr President <mrpresident@privatecompany.com>
Bad: Mr. President <mrpresident@privatecompany.com>
Good: Private Company <privatecompany@privatecompany.com>
Bad: Private Company, Inc. <privatecompany@privatecompany.com>

This isn't a direct solution, but would it be possible to use a 3rd party email marketing company to send your emails? This way you don't have to worry about a lot of these issues. ConstantContact.com is one. Eloqua seems to be a popular one for large companies.


Sign up for SNDS (https://postmaster.live.com/snds/index.aspx).

You will get better visibility on why Hotmail is blocking you - could be because your level of complaints is too high or you might be hitting spam traps (old expired Hotmail accounts).

You might also consider adding List-Unsubscribe header to your emails, but its usefulness (for Hotmail) is limited.

  • SNDS only gives data if you send a relatively high amount of mails, and doing so while being flagged as spam is a great idea for your company to loose its credibility. – user186340 May 6 '15 at 21:58

Contact JMRP see if they are blocking you again. We signed up and got blocked a second time till I contacted them.

Make sure you are unsubscribing the users who complain or they will block you again.

  • Yeah we enrolled pretty recently and I've never seen the issue resolved. So I don't think thats the case, unless they unblocked us one hour and blocked us again the next.. Yikes! – David George May 5 '10 at 17:28
  • How recently? Can take up to 48 hours. I am assuming you are past that point. I would contact them again and see if they can shed some light on it. Have you created a test account to see how emails are received? Are you receiving the JMRP forwards yet? – Campo May 5 '10 at 17:31
  • We signed up last Friday, so yeah over 48 hours. We haven't recieved any emails from JMRP. Yes, I've created a test account and that's why I posted the headers, that's the header the test account recieves. As per my previous posts, it's failing both X-SID and X-AUTH, which is making me leery that the problem is something besides JMRP blocking. – David George May 5 '10 at 17:49
  • I would agree but you said it is only hotmail that seems to block right? So you are saying that with the test account it sometimes goes to junk and other times goes to inbox? – Campo May 5 '10 at 18:04

We send daily mass emails to our customers

  • if enough people complain you will get blocked, you must unsubscribe the users that complain ASAP or you will blocked repeatedly.

For the x-sid error

verify that nslookup –q=TXT privatecompany.com and nslookup -q=txt TXT _spf.privatecompany.com return the right addresses

You should also have them add you to their database

  • We have an unsubscribe included in every email that goes to our clients... I'm not sure that blocking would cause the X-SID or X-AUTH to fail either. Thanks for the response Jim! – David George May 5 '10 at 17:27
  • Users are dumb. They won't see the unsubscribe. If they complain it is YOUR duty to unsubscribe them or you WILL be blocked again. As per my answer. – Campo May 5 '10 at 17:41
  • Senders that sign up for this program will receive any e-mail that is reported as junk e-mail. It's your job to unsibscribe these users immediately. If you are not recieving the emails I'd contact the JMRP admins and ensure that they have the correct email address. – Jim B May 5 '10 at 20:17

I get a lot of mass mailings which score high on antispam filtering. Mostly these are a result of violating standards applicable to email messaging. These include: Lines exceeding size limit; missing headers (usually message_id); invalid sender address; failure to encode data correctly; and incorrect DNS setup. I would expect these factors are considered by Hotmail.

DNS problems may result in rejection during when specifyinf the recipient. This could be interpreted as no such recipient.

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