Unlike with direct marketing which is mailing list often a 'one-off' campaign, you want to develop an ongoing relationship with your prospects. Even if you do not sell to them immediately, you may have a product or service for them in the mailing list future. It is easy to send people a series of emails. Many mailing list services promote this as part of their service, stating that you can write different messages in advance which they will send over the coming days, weeks and months.
This mailing list feature is expressed by some providers, for example the service provider will send a series of six emails over a period of two weeks and each email has a little more information aimed at tempting the customers to buy. But before you mailing list venture into your database with emails, put yourself in the recipients' shoes and ask how often you would like to receive e-mails and how many follow-ups you would think are reasonable.
It is best to send too few than too many, to prevent people from unsubscribing because they are fed up with receiving your emails. On the other hand, you do not want to communicate after so long that your prospects don't remember who you are. Try and find a balance between the two. Timing is very important when sending emails and will affect mailing list the success of your business. In most cases you will benefit in some months of the year than others depending on the demand of your product or service.