I'm new to Marketo, and I have noticed an issue when sending a Test Newsletter to myself. Microsoft Outlook makes the Newsletter different than the preview as well as Gmail. I'm aware that you can add a link to View email as a webpage but Is there a way to send a newsletter as a browser?
"Send a newsletter as a browser" -- I don't know what this means.
To develop email content that looks (roughly) identical in all mail clients requires either (a) an experienced, email-specialized HTML developer, or (b) templates purchased from a service run by such devs.
Like Sandford, I'm having trouble understanding what you mean by "sending email as a browser", but I'm going to take a guess at what you meant and try to explain:
Microsoft outlook is an application that is installed on computers, part of it's capability is being an email client - it fetches and displays emails from email servers.
A browser based email client, like Gmail or Hotmail, fetches and displays emails as well but you access it through a URL, like gmail.com, rather than installing and opening an application on your computer.
An email itself is just code and email clients interpret the code to display a nice looking email. The choice of using an application or a browser based email client is all up to the end user.