The biggest risk to your deliverability is having your email misidentified as spam. “Spam” is unsolicited commercial email messages.
We think of it first in connection with advertising, but spammers also use it to spread malware. Any electronic messaging can be a channel, including instant messaging, mobile phones, social networks, and so on, but it’s the most disruptive in an email.
Email Marketing: Spamming 101
Spamming persists because advertisers have no operating costs beyond the management of their mailing lists, and it’s difficult to hold them accountable. The estimated figure for spam messages (in 2011) is around seven trillion.
The costs, such as lost productivity and fraud, are borne by the public and by Internet service providers (ISPs). As a consequence, ISPs and industry groups doggedly work to develop ways to find and stop spam before it reaches the inbox.
It’s up to internet marketers to create email marketing campaigns and use sending protocols that are squeaky-clean and technically compliant, to avoid being identified as spammers and having their messages identified as spam.
Many webmail providers and spam filtering organizations take unused or abandoned email addresses (or B2B domains) and convert them into spam traps.
A spam trap is an email address used to lure spam so that the spam can be identified, then added to a blacklist or other blocking mechanism. In theory, a spam trap is an address that has never signed up for any commercial email whatsoever, so any mail it receives is considered spam.
Spam Cues Found in Written Content
Some of the distinctive content differences between wanted and unwanted email are due to the sender’s use of written language.
Absolute differences are due to senders of unsolicited email trying to hide their identity or their content. Many of them are due to the different quality software used to send each sort of email. Mail clients used by individuals, and content composition software used by high-quality service providers, tend to produce well-written code, complying with email and MIME standards, and standard practices for email form.
The software used by spammers, botnets, viruses, and low-quality email service providers tends to write bad code that is not compliant with industry standards.
As long as you are using a responsible, legitimate service provider to send mail, and are checking your content to ensure it meets industry standards, these filters should not cause you problems.
Spam Cues Found in HTML Structure
HTML structure evaluation is another aspect of email analysis.
Legitimate senders should always use valid and correct HTML. Spammers have long used fake HTML tags in an attempt to avoid filters; now some filters look at the tags and compare them with HTML standards.
Other spammers put random content in HTML comments as a way to confuse content filters.