While qualifying eMail for Spam, Hotmail/Live checks the historical records of numbers of eMails sent by a sender (FROM, eMail Server, IP, etc.). Some times, perfectly valid bulk eMails that are not Spam, (i.e. double opt-in list, from a server with proper SPF Record, signed with DKIM, unregister links and contact info, etc.) are rejected and not delivered to destinataries. Not even to their Junk folder.

I guess we can avoid this situation by progressivelly "training" Hotmail/Live about the reputation of our sender and sending small quantyties of eMails innitially and increasing the quantity for some amount/percentaje during each delivery.

Are there guidelines or do you have any experience on these quantities, strategy, solutions?

Thank you in advance.

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4 Answers 4


I've been in the email delivery software industry for years, and I can tell you that there is is no magic bullet for email deliverability.

First, you have to send email that people want to receive. This means email that people click, open, and use the email and that you get a low number of spam complaints. Confirmed opt-in is a great policy, and will gain you favor with ISPs, but you still need look at your email program from a subscriber's perspective. Are you sending what they signed up for? Did you tell them the frequency when they signed up? Are your messages well enough branded to be recognizable? Your complaint and user-engagement rates are large drivers of deliverability, so this is huge.

Second, you have to tweak. You don't know exactly what the rules are because the ISPs can't tell us. You start with changing things and see what solves the problem. You look for common problems. It helps to have done it before, so you can recognize patterns. Good old fashioned debugging.

Here's a list of things to try with Hotmail, based on my experience:

  • Sign up for Hotmail's JMRP (Junk Mail Reporting Program). They will send you a notification every time someone clicks on a "this is spam" button. Remove these addresses from your mailing list. This will lower your complaint rates over time.

  • Sign up for Hotmail's SNDS (Smart Network Data Services). This will provide a web-based login where you can get information on what they are doing with your email. You can also see if you have spamtrap hits and how many complaints you get.

  • Make sure your bounce processing is working. If you're sending to addresses you should have removed from the list but didn't, hotmail will count these against you.

  • Check to make sure that the HTML on your email is valid.

  • Check to make sure that your email has valid character sets. If you're sending Windows-1252 codepage characters and calling them ISO-8859-1 (latin 1) this can cause a problem with Hotmail.

  • Check your SMTP server transaction logs to see if Hotmail is giving you any specific guidance, such as error messages saying you have a low reputation.

  • Make sure you are not spreading your mail over too many IP addresses. You talked about keeping the volume "low". If you do this by spreading mail over multiple IPs, that can count against you, as this is a tactic called "snowshoeing" that is used by spammers.

  • Send at least 20k messages/day/IP to start with, so that you'll send enough mail to build a good reputation at Hotmail. If you don't send enough mail on an IP address, sometimes you don't give them enough data to build a reputation on you.

  • Realize that Hotmail's standard policy is to spam filter mail from a new IP address by not delivering it to either the Inbox or the Junk folder. This really is a pain because your mail completely disappears. They do this even to good senders. Then once you build a reputation, they will start putting the mail into the Inbox or Junk folders. There is a way that sometimes works to contact their tech support and have them reset this policy for you. (Contact me at [email protected] if you're interested in help.)

  • Try sending your message from a different well-established IP address and see if it gets filtered. Try sending other messages from this IP address and see if they are filtered. This can help to identify if the problem is IP-based or message-based.

  • Contact Hotmail. Don't ask them to un-block you off the bat, but ask why you're being blocked and what you can do to help fix things. With Hotmail you need to be persistent, replying to the same ticket multiple times if needed until you get to someone that can help you.

Ultimately you may want to hire a company that specializes in infrastructure for delivering email. Check out my company, www.drh.net. We provide email delivery software, consulting, and monitoring. We would be happy to help you.

  • @dharrisatdrhnet Thank you VERY much! This is a very well put piece of advice. You are covering a lot of surface here in a very clear way. We have already addressed most of what you say and the part pertaining my original question about an strategy to "train" Hotmail about our mailing is what I was looking for. It would be great if your answer had came at time for the bounty :(
    – vmarquez
    Commented Jul 23, 2010 at 12:42
  • Very good info here. I'll throw in a little bounty as soon as the site will let me award it. Commented Feb 6, 2011 at 14:16

Hotmail/Live is ... quirky. Much, much quirkier than other email services when it comes to "protecting" users from bulk email. You can find many complaints about Hotmail/Live all over the web about this stuff -- and it's true in my experience.

First, make sure you sign up using their SenderID forms.

The Sender ID SPF Record Submission Form will put your domains on their radar at least. It's kind of a semi-manual process, is the impression I distinctly got when working with them. If you want to send bulk mail reliably to hotmail/live users, you have to do this.

  • Thank you Jeff. That is a step we have already done and we are starting to try this theory of incrementing the quantity gradually.
    – vmarquez
    Commented Jul 12, 2010 at 11:36
  • If Jeff hadn't already answered you, I was going to quote his very own blog post about this very same subject. Alas, beaten to the punch by the master. codinghorror.com/blog/2010/04/…
    – Bryson
    Commented Jul 16, 2010 at 5:50
  • @Bryson That is a great post from Jeff. Thank you!
    – vmarquez
    Commented Jul 23, 2010 at 12:36

My honest advice would be to not do it yourself if you want reliable delivery without being flagged as a spammer. Use Campaign Monitor or aWeber or similar who are trusted senders of bulk email.

I hope this helps.

Cheers, Mark

  • Thank you but that is not an option for this client. Bulk eMail is an important piece on their service. People register with them to receive notices about promotions and offers. They (and we) think this must be managed internally.
    – vmarquez
    Commented Jul 19, 2010 at 3:14

Check these tips by andreas kraus for avoiding spam filters while sending automated mails based on his analysis of SpamAssassin (an open-source spam filter)

  • Those tips are focus on sending individual email and won't necessarily help to send large amount at the same time.
    – HoLyVieR
    Commented Jul 17, 2010 at 15:26
  • Thank you but my question is about a specific issue with Hotmail/Live that is triggered on the basis of volume. We are already dealing with SpamAssssin and other check types.
    – vmarquez
    Commented Jul 19, 2010 at 3:11

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