The address you're noting ("bounces+12345...") is the Return-Path address, not the FROM address. We overwrite the Return-Path address in order to handle bounce management for you. However, mailbox providers should be displaying the DATA FROM address, not that Return-Path address.
If you cannot resolve this on your side, you can tell us to not overwrite the address, but that will significantly hamper our ability to manage your bounces. Essentially, we will refrain from logging bounces or spam reports to the account suppression lists, and will subsequently not suppress future attempts to send to these recipients.