Saying hello / Greetings
hi
hi there!
hiya!
howdy!
hello
hi everybody!
what's up?
Good morning/afternoon/evening
We haven't seen for a while!
It's been a long time…
Such a long time!
It's been such a long time since we have seen each other!
I haven't seen you for such a long time!
It's good to see you again after so long!
(Long Time No See)
In Writing:
Dear Sir/Madam,
Dear Ms/Mr X,
To whom it may concern
For the attention of...