There are very bad news about how clever the filtering in Iran is, also the problem of government finding out the proxies and blocking them. there is one way that the government can't do anything about it. Iranians leaving outside iran can install Psiphon (
Psiphon - Wikipedia, the free encyclopedia) on their computers, then create accounts with user/password for their friends and relatives. Give your IP address and username and password by some other means than email, assume the government is reading what you send. call them, tell them the password in an indirect way (ie the name of the kid we used to play with + my birth day in ddmmyyyy format). use complex passwords.
government can't find all catered proxies and filter them, also Psiphon uses https and they can't filter that either.
help your friends in iran, create a proxy server at home.