It's more fun to send them plain, white envelopes with just their address on them so then they can't easily sort the spam from their business mail.
Speaking of spam, when you sign up for (whatever) be sure to list their email addresses as your "friends" who mightbe interested in (whatever). After all, the ACLU keeps telling us that they're our friends, right?
No because they might throw it in the trash can, while patting themselves on the back about that is one less person receiving the "Word"
Just DO NOT put talcum powder in said envelope unless you want to be some inmates "girlfriend."