HTML Email Best Practices

Here are some tips that I’ve learned working with HTML email.


  • Short and sweet (KISS – Keep It Simple, Stupid)
  • Include most important content towards the top of the email
  • Use stories to convey your message
  • Include one longer article that links to a web page with full article
  • A few shorter content pieces that stand alone and can be read without opening a browser
  • If possible, personalize using mail merge tools or, better, an email service (like Campaign Monitor)
  • Use consistent subject lines fewer than 54 characters
  • Avoid general spam trigger phrases – such as: “click here, go here, free, unsubscribe, …”
  • Avoid the use of CAPS and excessive punctuation marks (e.g. $$, !!!, …)
  • Provide your physical/mailing address and phone number.

Design & Layout

Around 75% of people who use email preview panes choose the horizontal version; the remaining 25% prefer the vertical version.

  • Design no wider than 600 – 640 pixels
  • Email clients’ preview (a.k.a. reading) pane is generally ~300 pixels high (~ 2 – 4 inches), so place your “attention getter” content towards the top
  • Layout in simple table row format (i.e. minimize columns to one if possible)
  • Test your design by viewing your email in appropriate email clients (e.g. Gmail, Hotmail, Outlook, Mozilla Thunderbird, …)
  • Background color should be designated as white (for WebTV and other users)
  • Do not use “background” images (e.g. text on top of images) since they are not consistently supported by email clients
  • Avoid the use of Flash, and javascript (for rollovers, etc.) – a common spam trigger and disabled in most webmail and email clients –
  • Remove/minimize header information
  • Maximize text-to-hyperlink ratio
  • Reference URLs that are as short as possible to avoid broken links


As many as 30% of email messages can be tagged as spam by content-based filters [source: Assurance Systems]. Free list management tools include Google Groups, Yahoo Groups, and Topica. To maximize deliverability rates and minimize spam filter problems, follow these guidelines:

  • Send emails early in the week – Tuesday morning works best
  • Maximize text-to-image ratio and minimize the number of images referenced
  • If possible, try to keep images smaller than 200 x 200 pixels – particularly header images
  • When possible, place images towards bottom of email (not the top/header)
  • If not using a professional delivery service, use a unique image in a unique directory location to track deliverability/open rates easily
  • Test your email deliverability by sending to test accounts (e.g. AOL, Gmail, Hotmail, Yahoo, …)

Subscription Management

  • Use “confirmed opt-in”(aka “verified opt-in” or “double opt-in”) practices to ensure subscribers want to receive mailings
  • Include comprehensive and easy-to-follow unsubscription information in each mailing
  • Remove undeliverable addresses from future mailings.
  • Develop, display and reference a Privacy Policy identifying all Personal Identifying Information (PII) collected by and for the e-newsletter and guaranteeing privacy, confidentiality and limited use of all such information.
  • Include the subscriber email address within the body of the email.
  • Use a reputable ISP or email delivery service for email delivery