Yes but MaxBulk Mailer has nothing to do with HTML code, what you write or paste is what will be sent as is. MaxBulk Mailer is only a software for sending messages. If the code doesn't work in the recipient email reader it is because it has a problem.
Things you can do:
- Remove the '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">' line.
- Replace the '<html xmlns="http://www.w3.org/1999/xhtml">' with '<html>
- Remove all those long comments from the CSS.
- Read: Guidelines for using CSS in email newsletters