I own a small business that sells hot tubs & hot tub chemicals to customers. I am looking for an email program that can email my customers when it is time to change their filters, time to drain thair spa, etc.

For example, if a customer, Jane buys a hot tub from us in November I would like the program to email her every 3 Months and tell her it's time to drain her spa. I would also like it to email her every November to remind her to come buy a new hot tub filter.

Any suggestions???

Thanks!