I have an Ubuntu 12.04 server with Postfix installed. In Postfix installation I used this guide https://help.ubuntu.com/community/Postfix. I didn't go through all of that, just the sudo dpkg-reconfigure postfix part.

I have created user accounts to my server and the users home directories contain a .forward file which have only one row the email address to forward to.

I have defined dns A records for the names www.mydomain.com and mydomain.com

But if I send an email to [email protected] it doesn't get forwarded. Actually I can't see any sign about any email ever visiting my server.

My firewall is defined to allow incoming traffic for ports 80, 443 and 22. For outgoing traffic it allows ports 587 and 22. The exact definitions are below.

Should I allow also outgoing http (port 80)? or maybe port 25?

# Allow ssh in
iptables -A INPUT -i eth0 -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT

# Allow incoming HTTP
iptables -A INPUT -i eth0 -p tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o eth0 -p tcp --sport 80 -m state --state ESTABLISHED -j ACCEPT

# Allow incoming HTTPS
iptables -A INPUT -i eth0 -p tcp --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o eth0 -p tcp --sport 443 -m state --state ESTABLISHED -j ACCEPT

# Allow outgoing SSH
iptables -A OUTPUT -o eth0 -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A INPUT -i eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT

# Allow outgoing emails
iptables -A OUTPUT -o eth0 -p tcp --dport 587 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A INPUT -i eth0 -p tcp --sport 587 -m state --state ESTABLISHED -j ACCEPT

Edits:

I found lines from my syslog telling me that there were incoming traffic for port 25 which was blocked. The sender ip's for those packages were trustworthy, so I opened also port 25. Now I can see some Postfix logging in my syslog. It looks like it is at least trying to forward emails. I haven't yet received any forwarder emails into my gmail mail box.