I have built a website and I have businesses registering which I am delighted with. However a number of companies are not completing their profiles.

I dont know if this is because they dont receive the confirmation email or the process is to long. I have emailed some of the companies but they dont respond.

The site is B2B and requires quite a lot of information as I need the information to make the site work. Some businesses fully register and enter all the details required.

Can anyone suggest how to improve the registration sytem or best practice for a registration system?