Answer:

ATTN

Answer	Crossword Clue
ATTN	Envelope dir.
ATTN	Letter abbr.
ATTN	Abbr. on an envelope

ATTN	Env. directive
ATTN	Env. notation
ATTN	Envelope wd.
ATTN	Please note (Abbr)
ATTN	Routing wd.
ATTN	Business env. marking
ATTN	Addressee footnote (abbr.)
ATTN	Envelope abbr.

ATTN	Abbr. on a business letter
ATTN	Envelope abbreviation
ATTN	Business-letter abbr.
ATTN	"Eyes only" abbr.
ATTN	Env. abbreviation
ATTN	Biz letter abbr.
ATTN	Letters on an envelope
ATTN	"To" on a fax

ATTN	Mailer's shorthand
ATTN	Abbr. on a memo
ATTN	On-envelope abbr.
ATTN	Name preceder on a bus. letter
ATTN	E-mail subject-line abbr.
ATTN	Routing abbr.
ATTN	Letter directive: Abbr.
ATTN	Memo abbr.

ATTN	Abbr. often followed by a colon
ATTN	Ltr.-routing word
ATTN	Ltr. directive
ATTN	Routing letters
ATTN	Corp. memo directive
ATTN	Directive on an env.
ATTN	Memo directive
ATTN	Abbr. indicating to whom it may concern

ATTN	Env. routing indicator
ATTN	Letters directing letters
ATTN	Letters that help a letter sorter
ATTN	Ltr. letters
ATTN	Ltr.-routing aid