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Email Deliverability Basics

Date: February, 2013 --

Countless direct marketers are expanding to digital and, as we all know, email is an especially effective marketing tool. Data from the US Direct Marketing Association shows it is the highest ROI-providing tool in the marketer’s toolkit at about 39:1. But, you have to get the emails to the right people in the right places and in doing so not jeopardize your ability to continue to do so. In short, you have to avoid the pitfalls out there that will cause deliverability issues and the outright blockage of your messages. Following a few simple, common-sense rules will ensure you maintain a sustainable and successful email marketing program.


Email senders are usually blocked or blacklisted by Internet Service Providers (ISPs) for one or a combination of the following reasons: high number of ‘toxic’ addresses in the file (including ‘honeypots’, ‘spamtraps’ ‘role accounts’ and similar decoys), high ‘bounce’ rates, and numerous SPAM complaints. A marketer can also be blocked by an ISP if there is an unusual spike in volume coming from their IP address regardless of the quality of the file or nature of the message.  


Email Addresses to Avoid:


‘Honeypots’ are used by companies almost exclusively for system security, so your emailing to such an address is an indication you did not get a reliable opt-in. This colors all other messages from your sending domain and adversely affects your ‘sender score’, which ISPs use to grade your reputability as a mailer, and can affect both deliverability as well as your inbox rate, i.e. the number of messages that are delivered to users’ inboxes vs. being delivered to a ‘junk’ or other bulk folder. Past studies have found that the presence of even one Honeypot record within your campaign can decrease deliverability by as much as 43%.


A ‘spamtrap’ is specifically created in a system, often by the ISPs themselves, and is non-public. Spamtraps are created primarily to deter marketers from utilizing ‘email address harvesting’ tools that crawl the internet collecting every possible email address from websites, as it is these tools which are most likely to pick up and be the source of spamtraps getting into an email database. In short, ISP’s associate possession of spamtrap addresses as a sign that you are not a reputable mailer, or at the very least not using permission-based best-practices to grow your email database. If you buy gray-market lists, or accept email addresses entered by visitors to your website without testing their authenticity, such as sending a confirmation email to get a double opt-in, you may also be at risk.      


A ‘role account’ is not a personal email account. It indicates an institutional function, such as, or An individual would not be expected to use such an address to elicit email offers or register to receive a newsletter, although this could legitimately occur. Thus, there is some bias for ISP’s to consider those sending emails to these addresses as suspicious, especially if they represent a large amount of the records within your campaigns.


A “bounce” rate is the percentage of emails coming from your sending domain to email accounts which are undeliverable. “Soft Bounces”, caused by full email boxes or a temporary network problem, do not by themselves represent a major concern for marketers; however, if the number is suspiciously high, you may have other data quality issues. In many cases, messages flagged as “Soft-Bounces” may ultimately get delivered.


On the other hand, “Hard Bounces” are returned because the email address doesn’t exist or is invalid. Invalidity could be for reasons ranging from a misspelled name to a non-existent name. On the B2B side, as happens quite often, a hard bounce can result from a person simply no longer working at the company for which you have his/her business email address, and that company simply closing down the account. A high number/percentage of Hard Bounces within your campaign can often raise a red flag with ISPs and cause your IP to be blocked.


Who complains to whom? Your Email Service Provider (ESP), or the sender you use to broadcast your email campaigns, will track complaints and other issues from various sources: individuals on your list as well as companies who maintain “blacklists” of mailers / IP addresses they’ve deemed as spammers, e.g. Spamhaus. Your own ESP may also become concerned should they notice a high amount of bounces and other issues with your campaign(s). After all it’s their infrastructure that is at risk of being shut down by these issues.


Email Data Quality Tips:

  • First of all, install thorough in-house customer-focused address hygiene practices.
  • If you have an online sign-up facility, use confirmation email practices to confirm deliverability and accuracy.
  • If you enter data takenfrom phone calls, exercise the same practice and caution. The error rates on staff-entered email addresses tends to be very high.
  • Maintain a robust ‘feedback loop’ to manage/suppress opt-outs and hard bounces as a priority matter.
  • Talk to your ESP. More than likely they’ll be happy to review your campaigns and provide you with some useful tips to improve deliverability and overall data quality. After all, your success means theirs as well.


Keep in mind email data quality must be looked as an ongoing effort as over time the accuracy of every list will inevitably depreciate due to an array of factors. People leave companies, new people are hired, companies close down and downsize, consumers move and abandon email addresses, and so forth.


So, the second thing to do is to ask Data Services to run its email hygiene protocols for you on a regular basis. They will confirm which addresses are deliverable and correct typos and syntax errors and work to remove the various “traps” described above. Keep deliverability numbers up, minimize exposure to traps and bounces, and capture that 39:1 ROI mentioned by the DMA.