Email not retaining formatting when sent - URGENT

Email not retaining formatting when sent - URGENT

I've created an email campaign in Zoho Campaigns which looks fine in the template. As soon as I send it as a test (thank god I sent it as a test first) half the formatting dissapears so text boxes don't have the correct margins and all the spacing between elements on the page are all over the place. 

My email campaign that needs to be sent out in 10 hours now looks like a junior school project.

Any idea on why this is happening and how to resolve it ASAP would be much appreciated.