An email's subject line and "from" address are "the most important factors" for getting users to open an email.

The revelation was made by Louise Rijk of Advanced Media Productions, writing for the UK-based Worcester Business Journal. She advised subject lines be eye-catching and less than 70 characters.

As mentioned in MarketingVOX's "13 Tips for Effective Email Marketing," a "From" name should be transparent. A message from Apple Store, for example, is less suspicious than something from "admin[at]apple.com."

Emails must feature the same logos and designs as the websites they represent, Rijk added.

She also advised examining how spammers use subject lines, then avoiding those methods.

A recent study found that "spam" is increasingly interpreted as "unwanted" email — not necessarily unsolicited email.