aerogramme
aerogram
airmail letter
air letter
inside address
mail-in
mailing
chain letter
titlecase
PS
postscript
mailpiece
airletter
block capital
mailer
monitory
round robin
delivery receipt
personal letter
mail
brief
ship letter
line
covering letter
cover letter
lenvoy
bullet
recorded delivery
dogsled mail
letterwinner
airmailer
posting
bounce
post office
special delivery
submission
missive
traveller's letter of credit
traveler's letter of credit
voucher
docket
chain email
stiff
airtel
postwoman
business letter
short letter
billet
note
frank