Microsoft is trying to dampen criticism by explaining its controversial decision to unify the rendering and editing engines in Outlook 2007 and use only the Word 2007 engine, even though there are some HTML and Cascading Style Sheet attributes that the engine does not currently support.

The move is a significant change from previous versions of Outlook, which actually used two rendering engines: Internet Explorer's engine was used for reading content, while Word was used for editing content when a user was composing messages.

Outlook 2007 now uses the HTML parsing and rendering engine from Word 2007 to display HTML message bodies.

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However, there are some HTML and CSS attributes that the Word 2007 rendering engine does not support, and Outlook 2007 now does not use the same standards as Internet Explorer 7.

The move has not been well-received by some bloggers, such as SitePoint's Kevin Yank, who said in a recent post that instead of taking advantage of Internet Explorer 7, Outlook 2007 uses the very limited support for HTML and CSS built into Word 2007 to display HTML e-mail messages.

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"This new rendering engine isn't any better than that which Outlook previously used—indeed, it's far worse," Yank wrote. "With this release, Outlook drops from being one of the best clients for HTML e-mail support to the level of Lotus Notes and Eudora, which, in the words of Campaign Monitor's David Grenier, 'are serial killers making our e-mail design lives hell.'"

Yank also noted that unless a user's HTML e-mails are "very, very simple, you're going to run into problems with Outlook 2007, and in most cases the only solution to those problems will be to reduce the complexity of your HTML e-mail design to accommodate Outlook's limited feature set."

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Asked about the controversial move, Chris Capossela, who manages the Microsoft Office System family of products, admitted that "in Office 2007, by default, when you write or read an e-mail in Outlook, we are using Word as the underlying engine for that."

The reason: Microsoft has done a lot of work to make Word the "best authoring and reading environment possible. So, when you are writing an e-mail, it's nice to get the spell-check capabilities of Word, or the ribbon capabilities of Word, right in that e-mail authoring and reading experience," he told eWEEK.

Microsoft has just released an document titled "Information on the Changes in Outlook Using Word as the Email Editor" to further explain its rationale for the move.

The document notes that, in the past, when people replied or forwarded HTML e-mails, previous versions of Outlook would first use Internet Explorer's rendering engine to view it, then would have to switch over to Word, the compose engine, when replying.

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"This wasn't an ideal experience for customers, as often the content people created looked different to the recipient receiving it—like the formatting would be slightly off, or things wouldn't appear as they had when the message was in 'compose' mode," it said.

"Added to that, one of the big things we heard in designing Outlook 2007 was that our customers wanted the rich editing tools they were used to from Word. Internet Explorer was not designed to be an editing tool for text, so using this tool was not the best experience for users," the document said.

The Word team made improvements in how Word 2007 handles HTML content, based on HTML and CSS standards and customer feedback, so the Outlook and Word teams made the decision to unify the rendering and editing engine in Outlook by using Word's engine and "give users a superior editing experience by using Word," the Microsoft document said.

However, while Microsoft acknowledges in the document that there are some HTML and CSS attributes that are not currently supported by Word's rendering engine, it says "the capabilities that our customers most wanted for their HTML newsletters are supported by Outlook 2007."

Next Page: "Something screwy going on."

But SitePoint's Yank disputes this, saying that he tested the two public beta versions of Outlook 2007 and "knew there was something screwy going on. Many of the newsletters I subscribed to had become unreadable, and SitePoint's own publications were looking decidedly unhealthy."

The solution? Use Microsoft's Outlook 2007 HTML and CSS validator tool, "to tell you which parts of your lean, mean HTML e-mails need to be replaced with old-fashioned HTML sludge. As a second step, you may want to consider giving your Outlook-based readers an easy way to switch to text-only e-mail. Bring on PDF e-mail. I'm ready," he said.

For Microsoft's part, the company has provided a list of HTML and CSS standards that are—and are not—supported.

As to why Outlook 2007 does not use the same standards as Internet Explorer 7, Microsoft said, "Customers using Outlook don't just want to display HTML content the way they do in their browser, but [they] also have an expectation that they should be able to author that content as well."

Read here about the release of Internet Explorer 7 for Windows XP.

Microsoft's document goes on to say that "a big thing we heard from customers is that they wanted the richness of the editing experience they were used to from Word integrated throughout Outlook. While Internet Explorer 7 is great, it was never intended to be an editing tool."

Does Microsoft plan to add support for the missing HTML and CSS standards to Word's engine? The company's response was vague: "The Word team is continually examining HTML and CSS support based on customer feedback."

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