Complaints can occur because users, in many e-mail programs, can report an e-mail as spam by clicking a special button.

These so-called feedback loop complaints are anonymously transmitted to promio.net by american providers, such as Hotmail, Yahoo or AOL, every time a receiver marks a mailing as spam. The user will be unsubscribed from promio.connect and will be added to the e-mail blacklist, or if they are in use, to the corresponding blocklist.