We recommend using a private domain though currently you are able to send campaigns using a free email address (public domain) such as Yahoo!, GMail, or AOL however there are some restrictions you should be aware of.
- As you are not the domain owner your control is very limited and therefore the Delivery Policies are controlled by the mail provider i.e. Yahoo!, GMail, or AOL.
- Free email service providers will have policies in place that may cause delivery issues, these are in place to prevent SPAM however can also have a negative impact on a legitimate emarketing campaign. SPAM levels can be reduced by using an SPF record on a private domain
Note: The list of restrictions may not be limited to the above, if you have any questions regarding limitations you should contact your mail provider for more information.
In order to obtain maximum results you should consider the positive impact on your campaigns by using a private domain as doing so will give you more control and allow you to create an SPF record.