
Working with emailers is tricky. The main reason is that most mail clients still aren’t advanced enough to handle today’s build technologies. In simple terms your email will be undeliverable. To succeed you almost have to take a step back in time to the late ‘90s and construct emails using tables and image-spacers.
The solution is wherever possible to stick to old-school HTML and use as little CSS as possible, using any CSS inline rather than relying on external style sheets.