how many mail you can send per hour ?

Sending mail from dedicated hosting o shared hosting is easy.

but the main part is how many mail you can send per hour ?

That's the question.
In shard hosting you can send 100 mail/hour.
In professional hosting you can send 750mail/hour
VPS - 3500 mail/hour.

But the mail can act as spam.So its risky to send mail.
If the limit you broke your server will be block.your IP address will be black listed.

All the best.