Consider this scenario:
Your organization uses patient information forms with a field for an email address, but without opt-in language — so it's not clear that when a person provides an email address, he or she will be added to your email marketing mailing list.
Not a big deal, right? Wrong. When those email addresses are collected and added to a subscriber list, two things are going to happen the next time you deploy an email campaign:
Simply put: The cleaner your list, the better it will perform. If everyone on your list has opted in, your open/click rates will be much better. Ultimately, you want people on your list who interact and take action. (Ask a retailer if they would rather have 10 customers who browse without buying, or two customers who actually make a purchase.)
With that in mind, it's a good idea to clean up your subscriber list from time to time. Even subscribers who opted in can lose interest. By monitoring your list regularly and removing inactive subscribers (or using a win-back tactic), the numbers will be better. It can also be helpful to identify when it's time to put extra energy behind promoting signups, keeping in mind that you should always be promoting signups.
For more e-mail marketing tips, download this white paper titled How to Develop a Digital Audience.