It is true that the 64 bit edition of Office 2010 is not currently supported. There should be no problem inserting the image you require. Sometimes difficulties occur if you have tried to cut and paste the content into the email from another document or email. I would recommend creating the email from scratch with Maximizer email window and using the insert image button on the tool bar to place your image in the email. This should work without a problem.
Also check that Maximizer is creating the email in html format as you will not be able to embed the images if set to text format.
Sometimes the appearance of a problem with images in an email can be associated with an overactive spam/mail filter which may have removed the images when you look at the sent email in outlook.