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How to get into Yahoo Inbox with your bulk emails

Posted on Feb 21, 2010 by Paul White

yahoo inboxYahoo runs one of the strictest Anti Spam setups of all the Free mailServers. If you send any kind of bulk emails then you likely haven't had much success getting into the inbox of yahoo.  Your Emails are either bounced with a deferred message, or they end up in the spam folder.  After switching IPs of mymail server I had the opportunity to validate many of my theories on how Yahoo's AntiSpam technology works.

If you have found yourself on this page you likely have filled out all Yahoo's stupid forms, and had them give you the same generic denied response each time.  In the mean time you continue to get bounce messages like these.  Reason: Remote host said: 421 4.7.0 TS01 Messages from temporarily deferred due to user complaints -

Respecting Yahoo and their network

First before we start this discussion, understand a few things.  Yahoo is in the business to make money.  The more spam yahoo lets in, the more storage they need, and the more servers they need to handle all the inbound connections.  The decision to enforce strict policies regarding spam has more to do with cutting costs, than it does with providing an excellent server for its users.  If you send a nasty email to yahoo complaining, its likely to be received by some under paid customer support rep, who deals with hundreds of these emails every day, yet they have no power to help you.  Their job is to simply take the heat, so that those in upper management can live in their fantasy land that they are not doing anything wrong.An Overview of YahooFirst before you get mad and put a fist through your LCD screen, its important to understand the bigger picture.  Yahoo has more members than any other Free Email Service provider.  With over 200 million world wide.  This also means they are the biggest target for spammers.  Yahoo sees more spam than any other provider.  This is for two reasons, 1. The majority of any maillist will consist of yahoo addresses.  2. Many people use their Yahoo email address for spam.  Meaning if they have to sign up for something, but are reluctant to give their real email address, they will often use a 2nd yahoo email address.  As a result the spam rate on these secondary email addresses is very high.

How Yahoo's Antispam technology works

Yahoo uses a number of technologies to block spam.  These include sending mail server IP reputation within the Yahoo system, various RBLs ( real time black lists ), user feedback ( people clicking the spam button ), DNS settings ( DomainKeys, DKIM, SPF, RDNS ( reverse DNS ), Senderscore ( found at senderscore.org ).  All these technologies focus on the hardware side.  But they also look at how the email is formatted, and what keywords are in it.  For intance if you have the word "Viagra" in your email this could potentially raise a red flag.  If you are using base64 encoding to mask your email text ( intentially or not ) this will also count against you.  If you are sending emails without alternate HTML / Text versions, this can hurt too.  If you are sending emails without a Named alias for the from Email, this also hurts.

How to get into the Yahoo Inbox with your bulk emails

When I say bulk emails this does not mean spam.  If you are trying to send spam these techniques can help, but ultimately your mail server's bad repuration will get you blocked.  When I say bulk email I am talking about any email message that is the same being send to mutiple  ( 100s, 1000s ) recipients.  Here I will list out all the things I have found that help and hurt your emails from being delivered to the yahoo inbox.

Things that help get into yahoo Inbox

  • Mail server uses DomainKeys
  • Mal server uses DKIM
  • Domain has proper SPF Text Record
  • IP has Reverse DNS pointing to the hostname of the mail server
  • From Email Address includes an Named Alias
  • Content-Transfer-Encoding: 7bit ( or any human readable encoding )
  • Mail Server IP has a SenderScore over 60
  • Joining the Feedback Loop and using its feedback to keep your maillist clean

Things that prevent getting into yahoo Inbox

  • Mail server uses no Key technologies ( DomainKeys, DKIM )
  • No Reverse DNS on IP
  • Content-Transfer-Encoding: base64 ( or any non readable encoding )
  • No SenderScore or a senderscore under 60
  • Sending high volumes of email from a mail server that typically does low volume daily
  • Sending emails that are 100% identical. ( add personalized header and footers to make them unique )
  • Mail Server IP listed on any RBL ( real time black list )

How to get Whitelisted by Yahoo

Yahoo doesn't have a whitelist, they determine how to handle your email based on your Mail Server's reputation.  But if you are having trouble with yahoo, and are getting the typical 4xx bounces ( deferred ), or messages are getting through but they are not making it into the Inbox, then you need to fill out a form.

Yahoo has a new bulk sender form, that allows you to tell yahoo what kind of mail server setup you have, so that they can route your emails to the appropriate folder. Fill out the Yahoo Bulk Sender Form here
Just be sure you are only sending emails to a double opt in list.  They are very strict about this.  They will check their system to see the reputation of your IP before approving you. Be honest with them.  One thing I have noticed with these forms is if you use the same IP for sending all types of mail, they will not prioritize your emails.  If you want prioritized sending you will need to setup a different ip and or hostname for different types of mail.  Newsletters and Marketing emails should not be send from the same mail server as your notifications / corporate emails.  This is how yahoo wants everyone to setup their mail servers.  Honestly I think they are asking for too much.

Check your open rates.

This one is very important, and I am still amazed how many companies don't check open rates.  They either don't have any kind of tracking built into their emails, or they use a third party that doesn't provide them with this information.  If you can get between 15% and 20% open rate tracking you are doing good.  Because many email system will disable your beacon images this is about as good as you can expect.  If you are using a third party to do a blast for you, ask them to reference an image off your server.  Then after they do the blast check to see what kind of hits this image received.  Only count the unique IPs.  This should give you a figure that is close to the number of emails that were opened.

A couple years ago my client ( a promoter ) paid another promoter to do a blast out to his list.  The other promoter claimed he had a maillist of 14,000.  But what he didn't know was the event flier that was called from our server had tracking built in to it.  So when he blasted out to his list we were able to see how many people really opened it.  The number was weak, only 300 could be confirmed as being opened.  We never did any work with this promoter again.  A maillist of 1 million subscribers isn't worth crap if you don't have a Mail server that is able to delivery your marketing to their inbox.  This is one of the problems with third party bulk systems like Constant Contact.  They use a shared block of IPs for all mail, and since they can't support the advanced technologies ( domainkeys, DKIM, RDNS ),  emails from them rarely make it into the inbox.  These systems are also constantly abused by spammers. 

Limiting Emails per Hour helps increase delivery in Yahoo

One thing I have noticed is yahoo does not like it when you try to bomb their servers with 20 SMTP threads at once.  If you want to make it into yahoo's mail servers its important the emails are delivered like they are corporate or notifications.  This means you don't want yahoo to see 50 emails that all look the same delivered with 5 minutes.  Generally yahoo should only see 2 or 3 emails from your server each minute.  Yahoo's system looks for patterns. As long as the emails you are sending do not look like bulk email yahoo will not treat it like so.  If you are able to setup your mail server to space out the delivery to yahoo this could increase your inbox delivery rates.  When yahoo starts to defer emails they typically remove the block witin 48 hours or sooner.  Its important to understand that this block is not manually added or removed.  The block is based on activity over a 48 hour time span ( theoretically ).  After 48 hours the emails that caused you to cross the line will fall off the back of the stack and you will once again be able to get into yahoo.

Staying within your normal daily traffic

If you run a community website.  Typically you might have 100s if not 1000s of notifications emails going out on any given day.  Yahoo knows this.  If on an average day lets say your mail server sends 500 emails, and then you blast to 10,000 people, Yahoo will know that something is different.  The trick is to send out a number of emails that is just barely above what you normally send.  This should keep your mail server under the radar.  This might mean letting your emails trickle out over a week, instead of blasting 10,000 within 10 minutes.

Send to your members first

Typically when doing an email blast they would go out ascending or decending, by database ID or date they joined the maillist.  But if you are like me, you have a separate members list, and maillist.  Members are active on your site, while the maillist are mostly just people who wanted to see some pictures.  To ensure the best outcome, send emails to your members first, then to your mailist ( newest subscribers first ).  This way if you get spam complaints it won't stop emails from reaching your active members.

Hardware matters with bulk email and yahoo

You can't buy high open rates.  You have to earn them.  If you are serious about running a legit mail server that will send bulk emails. I recommend you either buy a server and colocate it, or get a dedicated server with a hosting company that is willing to as many IPs as you need, and will not force you to use a Shared Mail Relay.  Those of you with godaddy dedicated servers will never enjoy high open rates because they block your outgoing port 25, and force you to go through their relay ( which has a bad reputation )

If you want it done right you have to do it yourself.

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