Please remember that these are general rules and do not provide a 100% guarantee that a filter will or will not tag your message.
When creating your subject line, try to avoid using the following words or characters:
!or multiple !!!, free upgrade, free gift, consolidate debt, $ or multiple $$$, Free or FREE, free offer or offer, Win a mortgage rate, Urgent, save $, apply now, New Customers, One time, please read, ALL CAPS, Prize, Order Now
Also, spell out digits…example (2.. use two)
HTML DESIGN REQUIRMENTS
Use HTML software such as Dreamweaver, MS FrontPage, or Adobe GoLive to create the HTML.Do not use MS Word, MS Publisher, or other graphics/desktop publishing software. Image Ready or Fireworks can be used in some instances along with HTML software for designs if used properly.
Use basic HTML tags for the coding. If your HTML software uses CSS for formatting, adjust the preferences to apply formatting using basic HTML tags only.
Do not use comments in the HTML code of your email as they can potentially flag spam triggers.
Provide a hyperlink to a related web site or at least an email address that the recipient can contact if there is not a web site available.
Keep the width of the HTML message under 650 pixels to ensure the design is not cut off in preview panes for recipients and to eliminate the need for scrolling horizontally to see the whole design.
Keep the message size less than 50KB for consumer emails, and fewer than 75KB for business emails to optimize download time and deliverability.
The more graphics/images there are, the more time it takes for a recipient to download. Potential customers will be lost if they have to wait for images to download in order to read or act on the message.
The higher the ratio of image-to-text area in an HTML, the higher the SPAM score. We recommend no more than 1/3 of the design area be graphics or images, and the rest should be formatted text. (more on page 2)
Many recipients have images/graphics disabled in their email account on emails from unknown senders, so they won’t see any information that is in the images/graphics. If they have formatted text in the HTML, the recipient can at least read the text part of the HTML if images/graphics are disabled. After being able to read the text and discover what the message is, they will be more likely to enable the images/graphics and act on the offer.
Print that is part of a graphic/image may display fuzzy or blurry, making it difficult to read. This happens because graphics/images are compressed or optimized to reduce file size and maximize download speed.
Do not use background images. Many email clients strip out the background images.