Question

How would you say goodbye and close an email to a friend whom you won’t see until summer?

Hasta mañana


Igualmente


Hasta luego.


Hola.

Answer 1

I would personally say Hasta luego, which means See you later

Answer 2

hasta mañana is see you tomorrow
igualmente is likewise
hasta luego is bye
Hola is hello
so I go with hasta luego but I rather say ¡Adiós! or ¡Ciao! which means good bye.