There are many options for sending bulk/mass email like newsletter or action alerts, and they range in cost from cheap or free to very expensive. We'll focus here on the less-expensive options:
Your Email Program (Outlook, Thunderbird):
Pros - cheap
Cons - being labeled a spammer by your ISP
List software included in your hosting package
Pros - cheap - already have it
Cons - limited tracking
Hosted bulk email tools like Groundspring's Email Now, Campaign Monitor, Vertical Response, Constant Contact, Mailchimp
Pros - quite good reporting and tracking on who opens/clicks/etc
Cons - varying degrees of integration with your database
Costs for Hosted Tools range - either pay on a monthly basis that includes a base number of emails you can send, or you pay per bulk mailing. Unless you plan to do a lot of bulk mailing, the pay-as-you-go option is probably most economical. Pay-as-you-go prices range, but generally include a flat fee per mailing plus a few cents per email sent. For example, Campaign Monitor and Vertical Response both charge around $25.00 to send a bulk email to approximately 1500 addresses. Prices vary, and change, so if this info is more than a few months old, get in touch with PTP to see if we have updated suggestions.
There is a third category for tools like Democracy in Action, and to a lesser degree TheDatabank and Salesforce. These tools are more integrated versions of the bulk email tools listed above, that have more robust data management capabilities. TheDatabank and Salesforce are both full CRM tools that can have bulk email added on to them while Democracy in Action is a designed as an integrated online engagement tool.
Of these three, DIA (Democracy in Action) has the most powerful and sophisticated bulk email capability, but as of this writing, it's data management lags far behind. Still, if you're planning complex bulk email campaigns that include pulling recipients in to sign petitions, donate, or otherwise get involved, DIA is well worth looking at. Prices for theDatabank and DIA vary, so contact them directly for a quote.