Most ESPs and ISPs have policies in place that prevent their users from sending spam, however not all of these policies are correctly enforced. Many times spam activity continues because there are no complaints being sent to an ESPs or ISP, or these complaints are being ignored by the abuse desk staff.
If your ESP or ISP is supporting spam by playing ignorant, you may begin to have issues with your own email. Moving to a new provider that has a strong anti-spam policy is your best option.
