Amazon SES Blog

Blacklisting (Part 2)

A few weeks ago, Jenn wrote about the “Address Blacklisted” error. As she states, “This error means that or one or more of the addresses in the To, Cc, or Bcc field of the email you just tried to send is on our blacklist.” In other words, you emailed an address that doesn’t exist and Amazon SES has temporarily blocked sending to that address to prevent further hard bounces.

I wanted to follow up and write about another meaning of the term “blacklisting” that is probably more universally understood in the email industry and how Amazon SES helps keep your mail going to the inbox. Many email receivers (e.g., Yahoo!, Aol, Hotmail, etc.) and reputation entities (e.g., Spamhaus, Spamcop, etc.) will “blacklist” an IP or domain they perceive to be sending low quality mail. When added to this list, sending can be inhibited. This is one of the ways the receiving community has fought off an influx of spam from infected zombies, Nigerian scams, and viruses. It allows the receiver to look at the connecting IP, cross reference whether it’s on the “blacklist” and then either deliver the mail or not depending on their internal policies.

We’ve seen questions on the Amazon SES forum about email receiver blacklisting. Please know that Amazon SES takes blacklisting very seriously and doesn’t find itself listed often. Sometimes we do, unfortunately. When listings happen, we work very hard with the email community to remove the listings as fast as possible. Usually, you’ll see a listing drop within a few hours.

Also note, not all blacklists are created equal. While you may receive a bounce from an ISP due to a blacklisting event, know that each blacklist has its own footprint in terms of impact on deliverability. In other words, some blacklists are used by many ISPs, where others are used by very few.

Blacklisting can occur for a variety of reasons, but the #1 culprit is mail going to spamtraps. This is a special address that has not opted in to your mail and has no human behind it. It’s simply a collection address created to see what mail comes through. If enough “hits” are collected with a spamtrap from an IP address, that IP runs the risk of being blacklisted. It is a good idea– especially if you’ve found yourself receiving blacklist bounces from ISPs–to double check how recipients are being imported into your address list and confirm you’re receiving permission to mail. Also, renting, purchasing or otherwise acquiring lists from 3rd parties can lead to spamtrap hits as well since no one has a “chain of custody” over the opt-in of the address.

At Amazon SES, we work with the email community by tracking ISP email requirements, monitoring blacklists, watching and reacting to deliverability monitoring, engaging in direct outreach, among a host of other activities to keep deliverability as high as possible. Please let us know if you have any questions about this and we’d be glad to answer either here or over at the Amazon SES forum.