Dedicated SMTP servers are the best option to choose if you are looking forward to sending Mass emails to your subscribers and for email campaign. As the SMTP servers for Yahoo, Gmail or MSN use shared IP addresses.
It checks if the sender account is an active account which acts as a first line of defense for your inbox.
Additionally, regular email providers have a limit of emails that can be sent in a day, for instance Yahoo mail has a limit of 100 Mails per day. Similarly, Gmail and msn also have some limits to the numbers of emails that can be sent in a day.