Unless you’ve recently taken residence under a hardened mineral formation, you’re probably familiar with January’s U.S. executive order that effectively bans travel from several specified foreign nations. There’s been all sorts of political and humanitarian debate about the ban, and rightfully so…but we’re not here for social commentary at the moment. Regardless of your thoughts on the ban and its originator, its existence could prove useful as a tool to better understand one of the most common issues that senders face: blacklists.

Blacklists and how they operate are often a point of confusion for senders. To help aid in understanding, let’s look at some of the ways the recent ban mirrors the process of email blacklisting.

1. Blacklist providers maintain a list of mail servers (usually designated by IP address) that are not considered “trusted” mail sources. This blacklist mirrors the list of countries included in the executive proclamation. The blacklist is designed to identify mail servers that have a history of sending spam or unwanted email messages.
2. Mailbox providers (Google, Yahoo, Microsoft, etc) use the data from the blacklist to check inbound mail. They check each message to determine if it originated from one of the listed servers, then determine how to proceed. In essence, each email provider is like a U.S. airport, receiving the messages and determining whether to allow them in based on the information provided by the blacklist provider (i.e. the Executive Branch).
3. If the source of a message is one of the blacklisted mail servers, that message will be disposed at the mailbox provider’s discretion. Some providers may choose to route the message to the Spam or Bulk folder based on the listing. Others will reject the message outright, returning a negative response to the originating mail server. This response sometimes provides specific details (i.e. this message was blocked due to Blacklist X) or may be more generic. These differences in processing messages from blacklisted servers draw parallels to the disjointed communication that occurred around the implementation of the travel ban. 

Another significant similarity between an email blacklist and the travel ban is the mixed receptions received by both in the court of public opinion. In the email industry, there are no shortage of folks who believe that blacklists are crippling senders, unnecessarily complicating the lives of people who desperately need to reach their intended audience. And of course, there are those of us who realize that blacklists are a vital part of the email ecosystem (even if dealing with them occasionally gives us headaches). I’m not sure the opinions are quite as heated as those over the travel ban, nor do I believe they should be.

One of the closest parallels between the two situations arises when a sender’s mail is sent from a shared IP address/mail server. This often happens to senders who are using an email service provider and do not have enough mail volume or send consistently enough to maintain their own server. When one or a small group of senders using that server are flagged for sending spam, the entire mail server gets blacklisted. Because of that blacklisting, all mail from that server – even the mail from senders who never sent any spam – could be rejected.

If you’re using a dedicated IP address, the best way to avoid blacklisting is to keep your list clean and engaged by regularly targeting and eventually culling non-engaged recipients, as well as avoiding sending to any list that was obtained without a clear opt-in. If you’re on a shared server, your best bet is to follow those same practices along with maintaining a good relationship with your ESP. If you’re using a reputable provider, the likelihood of problems will be lower and they’ll be quick to respond when issues arise.

Of course, there is one major, glaring difference between the effects of a blacklist and the travel ban: emails are important, but they will never be as important as people. Thanks for allowing me to indulge a bit of tongue-in-cheek discussion around a serious issue, and I sincerely hope the comparison has helped clear up a little of the confusion around blacklists. If you have questions about blacklists or anything else delivery-related, please feel free to reach out. 

– BG