Thanks for reaching out Community and well done. Cleaning your mailing list is definitely a best practice! Each month we determine your bill according to the size of your contact list. The price is based on the greatest number of unique email addresses in your Constant Contact account during the previous billing period.
You are correct your billing is reflecting a lower amount of contacts. Here is how to check your invoices within your account.
Additionally, if you do have further questions the billing team’s contact information can be found by clicking here. Let me know if I can assist you with anything else!