Should I Use External CSS in HTML Emails?

External CSS in HTML Emails: Feasibility and Efficiency

When composing HTML emails, a common question arises: can external style sheets be linked to, or should all necessary CSS be embedded within the email?

Feasibility of External CSS

In theory, it is possible to link to an external style sheet in an HTML email. However, webmail clients and email applications have highly restricted functionality, posing significant challenges to the reliability of such links. External style sheets are generally not supported and are unlikely to render properly across all recipient devices.

Efficiency Considerations

Assuming that external CSS linking does work, there is no significant efficiency advantage to using it over embedding the CSS within the email. In fact, embedding the CSS directly provides better control over the styles and ensures that they are applied consistently regardless of the recipient's environment.

Recommendations

Given the unreliability of external CSS linking and the lack of efficiency advantages, it is strongly recommended to avoid linking to external style sheets in HTML emails. Instead, embed all necessary CSS directly into the email's HTML code to ensure consistent styling and prevent potential rendering issues.

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