In fact, none of the theories for creating good HTML web pages holds true for creating good HTML emails!
In this article, David Greiner gives a good idea what should and shouldn't be done. Incidentally, this validated most of the stuff that we had already been doing based on our experience with various webmails & HTML email blasts/campaigns that we worked on.
Here are the summary of points given by him:
- Use tables for layout and as containers for background colors
- Use nested tables instead of margins & alignments
- Set the width of each cell instead of at the table level
- Use pixels instead of percentage widths
- Use inline CSS always
- Design with the assumption that images will not be visible by default
- Use "alt" text for images
- Aviod spacer images
- Always use image widths & heights explicitly
- Prefer JPG & GIF images
- Test, Test & Test more with various clients...
And now, some more considerations for mobile emails:
- Keep the total width to less than 600 pixels
- Be aware & design with consideration that text may be resized
- Test, Test & Test more with various devices...
Read the full article by David Greiner on 24ways.org for the details and the code here.