Sender Reputation

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The Importance of Sender Reputation

The most important factor in determining whether your message is marked as spam or goes in your subscriber’s inbox is your sender reputation score.   Sender reputation is associated with the IP address of the mail server you are using to send messages from.   ISPs score a sender’s reputation by giving different weight to various factors related to email marketing activity and then use some type of equation to determine your reputation.     In essence, your sender reputation indicates to ISP the trustworthiness of the source of the email that is being delivered.    What constitutes a trustworthy source will vary from ISP to ISP so in order to build a strong sender reputation you will need to familiarize yourself with all of the factors that ISPs look at when determining a score.

Oftentimes clients are baffled why emails that come from a brand new IP address would land into their subscribers spam box because they haven’t done anything “bad” with their IP address.   A brand new IP with no history of email activity is regarded suspiciously by ISP because they do not know anything about the IP address that is being used to send the mailings.   We compared sender reputation to credit history in a previous blog article.    

Clean Lists Improve Reputation

It’s important to stress the importance of list quality or list quantity with any discussion about sender reputation.   A high bounce rate, for instance, will damage your sender reputation.   Anything above 10% of your mailings bouncing is beyond the normal range of bounces and will raise red flags with your ISP.   As will a sudden spike in your bounce rate.   Particularly damaging is hard bounces such as invalid email addresses.  That is because spammers that purchase email lists have lists that contain a lot of bogus email addresses.    It is important to configure your email marketing software to use bounce management so that any invalid email addresses are automatically purged from your list.    Bounce management will also let you know how many hard bounces and soft bounces are occurring on your list.   You’ll also see bounce codes that report why a particular email address bounced.

A spamtrap is an email address that appears to be valid but is in fact used by ISPs to catch spammers. You will sometimes hear these referred to as “honey pots.”  Spammers use harvesting programs which scan millions of web pages looking for email addresses.  These email addresses may come from old email addresses which are recycled by ISPs in order to catch commercial emailers that use old, rented, or paid subscriber lists.  Some sites bury email addresses in their source code so that they are picked up by harvesting programs.  The company where the email originated is then alerted to any incoming emails that go to that address at which time they contact your web host and file a spam complaint.  Spam traps are bad news.   Its been reported that your delivery rate can drop as many as 20 points drop with one spam trap hit.   Spamtraps are one of many factors that ISPs look at when calculating your sender reputation.   Not only is your deliverability affected but they can result in temporary or long term blocks.

Good list maintenance is necessary for avoiding spam traps.   Here are some things you will need to avoid:

  • Poor List Sources -  This includes avoiding paid subscriber lists as mentioned previously
  • List Poisoning – Using confirmation Opt-In mailings will reduce the chances that you will receive invalid email addresses
  • List Aging -  Because spam traps are often used by recycling old email addresses use bounce management to remove any old email addresses and also remove any inactive addresses from your list.

Spam Complaints

If you are receiving more than one spam complaint for every 1000 emails sent then this can be damaging to your sender reputation.   Most people are familiar with the “Report Spam” button on their email client.   When this is clicked on a spam complaint is logged at the ISP level or it is also relayed back to the sender if they are a part of a feedback loop.  A good way to reduce your spam complaints is to ensure that all of your subscribers are opt-in.

Spam complaints do not track the reason why recipients make a spam complaint.   It is possible that even if subscribers opt-in to your list they may forget they are subscribed or no longer find your mailing relevant.  If you receive a high number of spam complaints on a list where your subscribers have opt-in to then this is usually a good indicator that your mailings are either irrelevant or sent to frequently.

Is Sender Reputation More of a Factor than Content?

According to a study by Return Path, 83% of deliverability issues were related to sender reputation.   Content of email was only a secondary factor.  Another interesting finding was that nearly 20 percent of legitimate mailings failed to be delivered.

The Importance of Sender Authentication

When people became aware of spam they learned to avoid any emails that came from unknown email addresses.  In response spammers learned to hide the true origins of their emails.  To combat this sender authentication protocols were established to verify that emails were coming from the addresses that they say they are coming from.   Now here comes the kicker.   Spammers are not only complying with email authentication standards but they are doing so at a greater rate than legitimate mailers. 

Why would setting up sender authentication help your sender reputation if legitimate email markers and spammers use them alike?  Sender authentication tells ISPs the IP address responsible for sending email to a particular domain.    ISPs can then monitor sending activity for a given IP address.    They will then know if a sender is abusing the permission they have been given to send out spam.   Their sender reputation will then suffer as will their ability to deliver mailings.  

In other words, in order to establish a Sender Reputation you should set up a Sender Authentication.   We recommend that at the very least you set up an SPF record