abstract
address
air
airmail
background
bank
banking
bills
blank
business
card
communication
concept
correspondence
currency
data
delivery
document
email
empty
envelope
express
finance
flow
information
internet
isolated
letter
line
mail
mailing
message
milk
money
open
package
page
paper
post
postage
postal
postcard
receive
send
service
stamp
swirl
wave
web
write