what do you write to end your letter/ email?

For formal letters/mails:

That's all I can say right now. I'm looking forward for your answer.

Truly Yours/Sincerely,
Felicia.

For informal letters/mails:

I guess that's all for now. Don't forget to reply; I'll be looking further about this. Have a splendid day.

Lots of Love,
Felicia.