Do webmail clients render emails with the browser they're loaded in?

Question

I'm generating content rich emails and want to ensure it will look identical on all clients. In order to test Gecko, Webkit, Trident and MS Word I've viewed my email in Firefox, Safari, IE and Outlook 2007 respectively. But with Gmail and hotmail etc, do those render emails just using the browser they're being viewed in?

Answer 1

Gmail and hotmail, themselves don't render HTML. The HTML portions of the email are rendered by the browser that they are being viewed in.

However, if Gmail, for example, presents a stylesheet, or embeded styles for the Gmail interface, it is possible for those styles to influence how the browser renders your HTML; however, they probably use class and id attributes that you are not using in your html, so it shouldn't be an issue.

Answer 2

According this report from the Email Standards Project, Gmail strips out all class and id attributes from emails.

...But even if Gmail supported embedded styles in the head of a document, it strips all IDs and classes from the source....

I sent their "Acid Test" to my Gmail account and it seems to be behaving as described.

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They also have a report for Hotmail, but I can't vouch for how up-to-date that one is.