Based on data gleaned from over 1700 clients worldwide, UK-based Emailvision has compiled a list of top 5 email marketing mistakes.

1. Trying too hard. Don't design an email as if it were a website — heavy use of Flash or Java may not render properly in a user's inbox. Keep it simple; let curious users click through to your actual web destination.

2. Right to reply. Some marketers make it a habit to enter an inaccessible return email address to avoid having to filter responses. Replies can provide valuable information — from problems with the email itself, to product inquiries. If you're concerned about filtering all that data, create a dedicated inbox for these messages.

3. Missing information. Ensure you have a comprehensive, segmented database. Nobody likes to be addressed as "Dear ______." In the web 2.0 world, customization is key; make users feel you know them.

4. All image, no text. Avoid sending purely image-based emails with no text. Some email clients, such as Gmail, suppress images unless the user confirms it wants the images displayed.

5. Stopped as spam. This is the most common issue — and probably the easiest to fix. Take care to avoid red flag keywords in your subject line, like "Win a prize" and "Free iPod."

"Companies can't afford to be making such simple mistakes and missing potential sales," said UK Managing Director Nick Gold of Emailvision.

"The fundamental aims of any campaign should be high deliverability, targeted mailing, maximum click-through rates and basic personalisation – don’t let the email be the reason customers go elsewhere."

Statistically, email, search and display advertising continue to return the strongest online performance. On its own, email has been shown to increase purchasing likelihood by 50%.