Particularly in a restaurant. When sending a personal message to friends and relatives take the time to copy and paste the same message into each one's separate letter rather sending it as one group letter. At least each friend or family member thinks it is a personal note instead of what it is, a stock message to everyone. This gives the false impression that you took the time to write to them individually. When receiving jokes via e-mail from someone you often sends jokes, remember to remove the sender from your list before forwarding it to your usual recipients.
Nobody likes getting their jokes back.
Always remove someone when they ask to be removed from your joke e-mail list and start sending them religious quotes. It will make them wish they were still receiving the jokes. Unless you hate the guy that sent you the e-mail. Then it is okay. Never flame somebody by sending an angry e-mail without thinking about the consequences.