What are the UX implications of using Web fonts in email templates? It seems that not all email clients support web fonts, but I'm not sure of the consequences of this.
Avoid using the custom font whenever possible.
Web font aka custom font is not pre-installed to your digital device. Is it an English/Unicode/Chinese web font? It takes time for user's digital device to download the font.
What if the email client does not support the embedded method of using web font?
What if the digital device is in offline/airplane mode?
What if the user's mobile device comes with a limited data plan?
Use Web safe font instead
Always add context for images
(Non decorative) Background image can be supplied with alternative text to enhance accessibility.
What if the email is classified as SPAM or highest secured mode is enabled so that image is hidden by default?
Litmus has some good recommendations on this that I've been following:
- Use a good base font (web safe)
- Enhance for the clients that support it
- Beware of Outlook
As long as you are prepared for the worst case scenario (with a web safe font), I think it's OK to offer a better experience for those who can support it.
The more similar the typefaces are (safe and not safe) the better it would be, of course.
As always with email, test on as many devices/clients as possible.