If you are searching good email service provider instead of Ymail/Gmail then I prefer Email.biz because it provides better features than gmail and ymail. Like: Universal login system, unlimited email storage, attachment up to 500MB, spam filter etc. Here I am giving you the stats on Ymail, gmail and email.biz which I achieved while sending emails.
* With Ymail I was able to send 100 emails and after that it says they cannot send more email in between 24 hours.
* Through gmail I was able to send 500 emails.
Through Email.biz you can send bulk emails to unlimited people.