The netrc file is used to save account information for various applications. Initially used by ftp clients only, now also fetchmail (amongst many others) has support for it.

Sample:

default
       login anonymous
       password georg.rind@wallbach.de
machine ftp.freebsd.org
       login freebsduser
       password secret
machine imap.provider.tld
       login emailuser
       password "even more secure"