I have set up a mail server using the tutorial for Ubuntu 8.04. Afterwards, I have attempted to set up access through Outlook Express. I set everything up, and checked the server needs to authenticate box for outgoing mail. When trying to send an email, it immediately comes back with Relay Access Denied. In my mail log, I see this: Jun 23 16:44:31 smtp pop3d: LOGIN, user=***@domainnet, ip=[::ffff:188.8.131.52], port= Jun 23 16:44:31 smtp pop3d: LOGOUT, firstname.lastname@example.org, ip=[::ffff:184.108.40.206], port=, top=0, retr=0, rcvd=12, sent=39, time=0 Jun 23 16:44:45 smtp postfix/smtpd: connect from s66-76-141-103.jsbrcmta01.jnboar.lr.sta.suddenlink.net[220.127.116.11] Jun 23 16:44:45 smtp postfix/smtpd: NOQUEUE: reject: RCPT from s66-76-141-103.jsbrcmta01.jnboar.lr.sta.***.net[18.104.22.168]: 554 5.7.1 <***@hotmail.com>: Relay access denied; from=<***@domain.net> to=<***@hotmail.com> proto=ESMTP helo=<workstation07> At some point, I found something online that told me to install a CA certificate for it to work with Outlook. I'm afraid this may have messed things up. Any help is greatly appreciated.