Це стара версія документу!
http://www.squirrelmail.org/about/
http://www.courier-mta.org/sqwebmail/
https://lists.debian.org/debian-user/2002/11/msg03898.html
cd /srv/www/cgi-bin/ ln -s /usr/lib/cgi-bin/sqwebmail
http://www.openspf.org/FAQ/Common_mistakes
http://serverfault.com/questions/369460/what-are-spf-records-and-how-do-i-configure-them