There are typically two types of pricing plans. Some services charge you based on the total number of emails sent, while others charge based on the size of your mailing list, allowing unlimited emails. (Some, like Vertical Response, offer both.)

Which service you choose will be based in part on how frequently you send emails and to how many people. At the Saskatchewan Jazz Festival, I have a moderate list size but send out a whack of messages each month leading up to the festival, so for me a list-based plan makes the most sense.

Vertical Response’s free nonprofit plan (which I believe is a response to the success of startups like Mad Mimi and Emma) can be a good looking option if you send less than 10,000 emails a month. Any more, however, and you can likely find a better deal elsewhere.

Other features also come into play, and you may find yourself loving the email building tool of one service, or the customer service of another. I would certainly recommend signing up for a few free accounts, and try building and sending a test message with each one. Don’t forget to check out the list management features, and see if the help desk is as attentive as they claim to be!