The term alias expansion is sometimes used to indicate a specific mode of email forwarding, thereby implying a more generic meaning of the term email alias as an address that is forwarded in a simplistic fashion.
This is particularly relevant in opt-out situations where the sender does not provide a reliable mechanism in the body of the message.
However, if VERP or BATV are being used (e.g. to prevent email backscatter), the electronic mailing list software will send individual messages to each recipient with a different SMTP FROM address.
The recipient's SMTP server sees only the forwarding system's IP address.
ISPs with low abuse thresholds may begin blocking email from the forwarding system.