E-mail marketing is when e-mail is used to communicate commercial or fundraising efforts to a target audience.   It is also used to:

• Enhance an exisiting business relationship
• Encourage customer loyalty
• Offer discounts and incentives for new customers
• Inform of the latest news and events

The actual content of the e-mail mesasge can take on various forms such as video, survey, newsletter, flyer, event calendar, etc.

The bottom line is that e-mail is used to keep in touch with people.  You can decide how often, the subject matter and the communication style.  Just be mindful that most people receive a lot of e-mail, have time constraints and delete messages that do not capture and hold their attention.