I do know for certain that on ICCF engines are allowed, but the question is whether analyzing the position with a human is allowed? I know that on chess.com if you let someone play on your profile you will get banned. The reason is that if it's allowed I am planning to post a question regarding my current position on a game on the ICCF.
Yes, it is legal.
ICCF: Says nothing about it, or assistance of any kind, and you can even use computers legally. Here are their rules.
USCF: "3. You may consult chess books and periodicals but not other players." Here are their rules.
With regards to the ICCF rules, my guess is that they just decided it was too hard to police computer used, so they just allow it. Books have always been permitted. Human assistance also.
NO, it is NOT legal to analize an ICCF game position with another human. The only exception is in team tournaments where it is allowed to consult with the team captain and members. According to article 2.15.5 of the rules valid from Jan. 2020:
2.15 Code of conduct
- Obtaining advice from another person about an active game: It is expected that players will decide the moves for themselves. It is unacceptable behaviour to have someone else play your games (for instance playing “mirror games” is not acceptable). TEAM: Consultation between/among currently listed players of a team including the team captain about positions in active games in their team event is acceptable behavior.[Congress decision 2019]
Previously (2019 rules, article 2.15.5), it was not legal to consult with anyone else, not even team partners.
In addition, article 2.2.6 of the 2020 ICCF rules states:
2.2 General rules and procedures
- 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.
When I played in ICCF, the rules were any sort of reference help other than another person was allowed. That was mainly books back then. I had wondered if Berliner had used his IBM access to help win the world championship in the '60s.
Now understand that they specifically allow computers as well as books. There is no way for them to know if someone is using another person. So the only thing stopping it is your ethics and conscience.
Why bother playing postal chess if you are average and then getting someone to help you? And if you are a top player, then good luck finding someone who could help you better than you and your computer can do.