Email Sending Limit
While there are no limits in place on the amounts of emails that you can send, we do ask that your email campaigns abide by our Terms of Service.
In addition, you campaigns need to be CAN-SPAM compliant.
There's another post that goes into some really good detail about email campaigns:
Another thing to keep in mind is that if you're creating a new account, your Linode's mail ports (25, 465, and 587) will be blocked by default. In order for those port filters to be removed, you'll need to open up a Support ticket telling us a bit about your Linode and your planned email campaigns. We have a blog post that goes into detail about this: