Some mail programs automatically use the From address when a contact replies to your campaign or to send bounce replies. There is no way to determine which will be used per server. In order to improve bounce handling and reporting for campaigns, use your bounce address as the Reply-To and From Addresses.
For example, when a contact replies to the email with "Unsubscribe" or "Out of Office", the bounce handler will track and discard those messages automatically. Any other valid replies are forwarded to the customer service address.
To prevent a personal or important mailbox from being flooded with replies, use the bounce address, or a form of the bounce address, for both From and Reply To, and then setup a Customer Service address for the bounce mailbox to forward replies. (Please contact your TAM to setup your Bounce Mailbox if necessary).
For example, if the Bounce Mailbox address is:
Bounce: MAILBOX??EMAIL_REF??@sub.domain.com
you could use the following From and Reply To:
From: MAILBOX@sub.domain.com
Reply To: MAILBOX??EMAIL_REF??@sub.domain.com
Notice that the From address does not include ??EMAIL_REF??. This is because this portion is automatically generated for each contact and each newsletter. If a contact wishes to add the From address to a 'safe' list, this re-generated portion would make it difficult.
With this setup, all replies automatically route through the bounce handler. Any messages that the bounce handler cannot match to known bounce messages will be forwarded to customer service. All recognized messages are counted as hard, soft, block or abuse/complaint bounces.