How many cold-emails to test a niche?

Recently got into email marketing and I've just got the results back from my first campaign.

Cold emails sent: 784 (single sequence)
Positive replies: 0
Negative replies: 11

I'm curious about a couple things:
Is 784 too small of a data pool to test a niche?
Am I targeting the wrong niche (should I have at least 1 positive reply by now)?
Where is the best place to get leads for businesses who use telemarketing/cold-calling? Is it LinkedIn?
Should I only be contacting CEOs?

For B2B mailing, even 100 emails are good enough to get business started. You have to make sure their requirements rather than mailing random niches.

Good Luck

784 emails is a good number to start, but 0 positive replies suggests you didn't do one, or all of the following:
1) Finding out the correct email address.
2) Segmenting your email lists.
3) Writing decent, personalized copy so they are at least interested.
4) You aren't selling an interesting product, or at least the product isn't interesting to your audience.

Next time I suggest you send your emails in smaller batches of 30-50 emails, each targeting different types of potential customers. Do this 4-5 times, measure the results and replicate the most succesful batch at a larger scale.

Make sure that your emails are personnalized.

Make sure that your offer solves a real painful business problem.

Don't send HTML emails, just text emails. You're a company owner writing to another business owner.

Focus on getting testimonials

784 are related to your niche?
784 have a problem than need addressed and your provide a solution to that problem ?

negative = is a good thing, show you that they receive you msg and read it
no positive = 3 maybe more things

1 Offer issue
2 Targeting issue
3 Script issue

Each have it own strategy in mind. To have good stats you need more emails. Some Suggest 10k per month.