iptables and incoming email blocked

I have postfix and dovecot installed and my emails work fine

• I can send emails out (local and external)
• I can receive emails in (local and external)

If I start building a firewall with iptables, I start to encounter problems.

• I can send emails out (local and external)
• I can receive emails only if it was sent from inside my domain.
• External emails trying to come in simply ‘disappear’. (I am connecting via POP3)

Here are some of the references that I have been using Digital Ocean How to setup a firewall with iptables Ubuntu Community iptables

Here are my iptables rules sudo iptables -S

-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p tcp -m tcp --dport 22 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 25 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 80 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 587 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 110 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 143 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 995 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 993 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 443 -j ACCEPT
-A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables denied: " --log-level 7
-A INPUT -j DROP

Now when I send an email in from outside my network, this is what I see in my syslog in regards to the dropped packed.

Oct 21 17:40:09 breia dovecot: pop3-login: Login: user=<test1>, method=PLAIN, rip=58.173.60.47, lip=128.199.130.239, mpid=1381, TLS, session=<SsXjrPUFvwA6rTwv>
Oct 21 17:40:09 breia dovecot: pop3(test1): Disconnected: Logged out top=0/0, retr=0/0, del=0/0, size=0
Oct 21 17:40:30 breia kernel: [ 4253.135412] iptables denied: IN=eth0 OUT= MAC=04:01:2c:93:28:01:4c:96:14:ff:ff:f0:08:00 SRC=95.183.244.29 DST=128.199.130.239 LEN=40 TOS=0x00 PREC=0x00 TTL=244 ID=54321 PROTO=TCP SPT=39141 DPT=135 WINDOW=65535 RES=0x00 SYN URGP=0
Oct 21 17:40:46 breia postfix/pickup[1030]: trigger_server_accept_local: trigger arrived
Oct 21 17:40:46 breia postfix/pickup[1030]: master_notify: status 0
Oct 21 17:40:46 breia postfix/pickup[1030]: master_notify: status 1
Oct 21 17:41:27 breia kernel: [ 4309.962349] iptables denied: IN=eth0 OUT= MAC=04:01:2c:93:28:01:4c:96:14:ff:ff:f0:08:00 SRC=64.189.75.2 DST=128.199.130.239 LEN=88 TOS=0x00 PREC=0x00 TTL=55 ID=0 DF PROTO=UDP SPT=53 DPT=33407 LEN=68

From Understanding iptables log, I have some understanding of what the log file means.

Could someone please help me to understand further what is happening, and how I can fix it so that I can receive emails from outside my domain.

Thank you,

Brent