Sending but not receiving mail, why?

Question

SMTP

Put a miracle socket brainycp.
I set everything up, everything stood up clearly, but mail from the world does not reach.
this goes away perfectly.
I try to knock on port 25 from the outside and from the inside:
the answer is one

Connected to youmail.my-mails.ru.
Escape character is '^]'.
220 youmail.my-mails.ru, ESMTP EXIM 4.92.3
421 youmail.my-mails.ru: SMTP command timeout - closing connection
Connection closed by foreign host.

tried from inside telnet 127.0.0.1 25 and 78.108.88.73 25
similarly .........SMTP command timeout - closing connection..........
telnet knocked on port 110 - all OK

Trying 78.108.88.73...
Connected to youmail.my-mails.ru.
Escape character is '^]'.
+OK Dovecot ready.

watch
nmap -v -p25,110,143,465,587,993,995 127.0.0.1

nmap -v -p25,110,143,465,587,993,995 78.108.88.73

Starting Nmap 6.40 ( http://nmap.org ) at 2019-11-30 18:31 MSK
Initiating SYN Stealth Scan at 18:31
Scanning vm26731 (78.108.88.73) [7 ports]
Discovered open port 993/tcp on 78.108.88.73
Discovered open port 25/tcp on 78.108.88.73
Discovered open port 587/tcp on 78.108.88.73
Discovered open port 110/tcp on 78.108.88.73
Discovered open port 143/tcp on 78.108.88.73
Discovered open port 995/tcp on 78.108.88.73
Discovered open port 465/tcp on 78.108.88.73
Completed SYN Stealth Scan at 18:31, 0.02s elapsed (7 total ports)
Nmap scan report for vm26731 (78.108.88.73)
Host is up (0.000048s latency).
PORT    STATE SERVICE
25/tcp  open  smtp
110/tcp open  pop3
143/tcp open  imap
465/tcp open  smtps
587/tcp open  submission
993/tcp open  imaps
995/tcp open  pop3s

Read data files from: /usr/bin/../share/nmap
Nmap done: 1 IP address (1 host up) scanned in 0.08 seconds
           Raw packets sent: 7 (308B) | Rcvd: 20 (856B)
*************************
Starting Nmap 6.40 ( http://nmap.org ) at 2019-11-30 18:28 MSK
Initiating SYN Stealth Scan at 18:28
Scanning localhost (127.0.0.1) [7 ports]
Discovered open port 587/tcp on 127.0.0.1
Discovered open port 993/tcp on 127.0.0.1
Discovered open port 143/tcp on 127.0.0.1
Discovered open port 110/tcp on 127.0.0.1
Discovered open port 995/tcp on 127.0.0.1
Discovered open port 25/tcp on 127.0.0.1
Discovered open port 465/tcp on 127.0.0.1
Completed SYN Stealth Scan at 18:28, 0.02s elapsed (7 total ports)
Nmap scan report for localhost (127.0.0.1)
Host is up (0.000086s latency).
PORT    STATE SERVICE
25/tcp  open  smtp
110/tcp open  pop3
143/tcp open  imap
465/tcp open  smtps
587/tcp open  submission
993/tcp open  imaps
995/tcp open  pop3s

Read data files from: /usr/bin/../share/nmap
Nmap done: 1 IP address (1 host up) scanned in 0.08 seconds
           Raw packets sent: 7 (308B) | Rcvd: 20 (856B)

netstat -na | grep :25

tcp        0      0 78.108.88.73:25         0.0.0.0:*               LISTEN
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN
tcp        0      0 78.108.88.73:25         92.118.38.38:17408      ESTABLISHED
tcp        0      0 78.108.88.73:25         92.118.38.38:38556      TIME_WAIT
tcp        0      0 78.108.88.73:25         92.118.38.55:26694      SYN_RECV
tcp        0      0 78.108.88.73:25         92.118.38.55:29166      SYN_RECV

iptables -S

-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT
-A INPUT -p tcp -m tcp --dport 11211 -j DROP
-A INPUT -p udp -m udp --dport 11211 -j DROP
-A INPUT -p tcp -m state --state NEW -m tcp --dport 20 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 21 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 25 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 53 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 110 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 143 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 443 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 465 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 587 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 993 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 8000 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 4747 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 30000:50000 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 8002 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 3306 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 43 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 5432 -j ACCEPT
-A INPUT ! -s 192.168.1.0/24 -p udp -m udp --dport 111 -j DROP
-A INPUT ! -s 192.168.1.0/24 -p tcp -m tcp --dport 111 -j DROP
-A INPUT -s 127.0.0.1/32 -p tcp -m tcp --dport 111 -j ACCEPT

what he doesn’t like, I can’t understand but how
the logs are empty, according to my question

Answer 1

Probably selinux enabled