There are marketing companies sell customer databases. Hotels and resort, credit card companies, insurance companies like to buy them and start doing their marketing. I am in the marketing field (ICT) but i find email marketing nowadays are extremely annoying and most of my clients (no to mention prospective customers) regard them as junk mails and it will just be deleted without reading your ad.

You are actually asking how you can spam over 20,000 people. Is that how you really want to promote your business?

Do it the professional and effective way and build your list. Have a look here:

If this is the way you want to market your company (not always the best way), you will need to purchase a list from a list company such as dbs data.
Once you have your list, you can either ask them to send out your ad in-house, or, you will have to purchase an email program such as itellicontact to send the email out on mass. This article should help:
Good luck!

Check out ( )
That site has a lot of great info and good ideas.
They have a whole section on email marketing.

Many magazines sell their subscription lists. Many of them have emails.

I think you should not only get a list of random individuals from a hotel chain, but try to target various magazines that deal with phone systems, for example, and therefore you are advertising to a market that is ready for your service. You just need to be ready for their business. Good Luck ArmenH