I'm about to send a business proposal to a person who doesn't know me. The document volume is equivalent to about 6 pages (A4, single spaced). I can create a nice looking PDF optimized for screen view and send it as an attachment. In that case the mail would say "hello, my name is Blah Blah, I have a proposal that deals with this and that, please open this file. Another alternative is to sent everything in an HTML-formatted e-mail.What do you think is the better approach?
Don't send the proposal with your first message. It will shut the door close into your face and any following attempts will be perceived as stalking.
Why are you sending it to this person? I got it that you don't know him/her, but do you know anyone that may have an access to this individual. If not, don't be too aggressive. Send a letter, email or text introducing yourself and ask if it will be OK to send a short proposal. If you get response, you can take the next step.
Your problem is not in formatting of your proposal, but how to get your message across. Play it smart.
I would probably go with the PDF - I'm just learning now how hard HTML email is!
Having said that, I don't think I would respond well to receving a 'business proposal' that is unsolicitied and completely cold.
Maybe try to build a bit of a relationship with your contact first?
Maybe just introduce yourself via a mail or a call, explain that you have a proposal that he may be interested in, and ask permission to send it over?
Or take out the key messages and summarise and generalise your proposal into a shorter paper that could be sent through to the person as marketing collateral. It can still be tailored to his business and specific problem, but feels like a more natural business interaction.
A proposal like the one you described would usually come much closer to the point of sale when you have a good understanding of your customers problems and want to formaise the project. I think it is rare that unique six page proposals are used as marketing tools, but I may be wrong.
The big issue is figuring out to connect with the person. If they are at a high-level in the company they probably get dozens of unsolicited emails a week and you need to get through the initial deletion of your email.
As others have said you need to figure out how to build a relationship with them before you have any chance of them even reading your email, let alone your proposal. I would try:
In general, look at your inbox, figure out what you read and what you don't and why and try to apply that to what you are going to send out.