WordPress / BuddyPress Not Sending Emails to Hotmail

I ran into a big pain of a problem a few days ago and spent the next few days solving it with the generous help of Josh and Dave.  So here we are.  Problem solved (hopefully).

The issue we were experiencing was that my WordPress installation was not able to send email to Hotmail and Mailinator email accounts.  It was sending them just fine to Gmail and Yahoo email accounts.

Quite literally, the emails were disappearing.  There was no record of them being lost.  No bouncebacks.

After testing and checking all sorts of things [spam filters, SMTP, mail(), plugins, etc., etc., etc.] we discovered the problem was that our IP was blacklisted.

Basically, email companies use different algorithms and services to determine what messages belong in spam, what messages belong in trash, and what messages get into the inbox.  Unbeknownst to me a few hours ago, it is also possible that emails will go to none of the above.  They will literally just be lost without a trace.  Amazingly frustrating.

To solve the problem, we first made our way to mxtoolbox.com and used their blacklist checker.  We were on the blacklist for 2 out of the 105 in their list.  But aparently those two are big ones.  I don’t even remember which lists they were.

We had to go to the blacklist manager tools for each of those two lists and request a de-listing.  Within an hour emails were flowing like the Mississippi in August.

All in all, the problem took not to long to solve once we knew what the problem was, but I bet we spent 40 hours trying to get there.

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Toby Cryns

Toby Cryns is a freelance CTO, expert WordPress consultant, and teacher.

He offers free advice to improve your freelance biz.

He also publishes small droppings every now and then to twitter.com/tobycryns and twitter.com/themightymo

Follow Toby's contributions on Github and WP.org.


  1. MxToolBox Support on July 14, 2011 at 3:30 pm

    Thanks for recommending our Blacklist Tool! We wanted to let your readers know that our Monitoring Tool can send you alerts if your server is Blacklisted, server is down or if your website is down, all automatically. Sign up here:


    Thank you!

  2. toby on July 25, 2011 at 12:18 am

    @MxToolBox Support – Normally I don’t allow shameless plugs on this blog, but in your case, I will make an exception. 🙂

    Thanks for providing a great service!

  3. Colin Smith on February 6, 2012 at 12:47 pm

    Hi. I have done the backlist check and found several timeouts. I am not sure how to clear them. Any help would be really appreciated. Causing me a lot of grief. as you well know.
    Many thanks

    • toby on February 16, 2012 at 3:39 am

      I would guess that there is nothing you can do about those timeouts, as they are on the blacklist checker end of things.