Sender addresses are often forged in spam messages , including using the recipient 's own address as the forged sender address .
Responding to spam may result in failed deliveries or may reach innocent e-mail users whose addresses have been abused .
Sender addresses are often forged in spam messages , including using the recipient 's own address as the forged sender address , so that responding to spam may result in failed deliveries or may reach innocent e-mail users whose addresses have been abused .