when people give you their email to be added to your newsletter group, what do you do with people who repeatedly come back as unable to deliver the email? i got a stack of leads at my last 2 boothes and specifically told everyone "if you are interested, give me your email for my newsletter". i thought i had made it clear that it wasn't a requirement. so why would they purposely give me bad emails? so, should i try calling or should i cuyt my losses?