factors affecting email deliverability

Email Sourcing – Factors Affecting Email Deliverability

Landing email campaigns in recipients’ inboxes isn’t always easy. In fact, there are a number of factors affecting email deliverability that you may not even be aware of, including minor faux pas that can land you in the spam folder.


Email Deliverability Defined

Email deliverability is the percentage of emails from each campaign that reach their intended destination without getting lost in the great abyss of blacklists and spam folders. Unfortunately, spam is one of the major factors affecting email deliverability.


The History of Spam

Unsolicited junk messages have been coming across the wire since the early 1800s, but the modern version of spam (a term lifted from a popular Monty Python sketch) started with Gary Turk’s computer advertisements across a military computer network in 1978.

Today, unsolicited junk mail accounts for 86 percent of the world’s email traffic, with approximately 400 billion spam messages being sent each and every day! Luckily, more than 99.99 percent of those junk messages are blocked by one of the major factors affecting email deliverability — modern anti-spam filters.


How Spam Filters Work

Many of the factors affecting email deliverability make up the criteria used for spam filtering. These items are weighed and calculated to assign a spam score to your email campaigns. But what constitutes a passing score varies from server to server.

If you think you’re safe because you’re using a homegrown, permission-based list, think again. Even opt-in campaigns get flagged by overly aggressive spam filters.


Common Types of Spam Filters

  • Header spam filters: Headers identify the origin of an email, revealing items such as ID and IP address. If information in your header appears to be forged, or just happens to match up to that of known blacklisted spammers, you won’t reach the inbox.
  • Content spam filters: Several factors affecting email deliverability may be present in the text of your message, including language that is adult-oriented (Viagra), money related (Free!) or urgent in nature (URGENT). Odd punctuation, ALL CAPS, attached .EXE files and links to blacklisted websites can also raise red flags.

Keep in mind, a combination of header and content filters are often used to obtain the most accurate spam score.


Metrics and Other Factors Affecting Email Deliverability

Keep an eye on bounce rates, the percentage of emails returned as undeliverable. Hard bounces are invalid, blocked or non-existent addresses. Soft bounces are temporarily undeliverable, usually due to a server issue.

Spam complaints are subscribers who have reported your campaigns as spam, and unsubscribes come from users requesting to be removed from your list. (Too many of these may indicate a problem with content direction.)

Other factors affecting email deliverability include spam traps and honey pots. Data cleaning can eliminate these problems, but traditional ESP and marketing automations don’t clean data upon import. This is especially important with cold and purchased data. To handle this data properly, you’ll need to use email lead generation software.

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