can i use engine in correspondence games?
You can't; that is cheating!
Here you are not allowed, but the International Correspondence Chess Federation allows it.
you can use a database, a book, but an engine is considered cheating. I didn't know the ICCF allows engines
6. In ICCF event games, players must decide their own moves. Players are allowed to
consult prior to those decisions with any publicly available source of information
including chess engines (computer programs), books, DVDs, game archive databases,
endgame tablebases, etc. TEAM: In addition, acceptable behavior includes
consultation between/among players of a team including a team captain about positions
in active games in their team event. No other consultation with another person
concerning analysis of an active position is allowed in either a team or individual event.”
You can't post in the forums yet. Play some games!