SMTP Port 25 Connection Issue - Mail Server

aaP_rodrigo-rios

I am experiencing an issue with my mail server configuration. Although a port check tool indicates that port 25 is open, I am unable to establish a connection via Telnet. Here are the details of the issue:

Using the command telnet mail.mydomain.com 587, I can successfully connect.
However, using the command telnet mail.mydomain.com 25, the connection fails.
Additional Information:.
Port 25 appears as open on online port check tools.
Port 587 works as expected without issues.
I have configured Postfix and Dovecot to handle email delivery.
I will attach screenshots of my configuration files and relevant settings for your review. Please let me know if there are additional diagnostic steps or configuration adjustments I should make to resolve this issue.

Thank you for your assistance.

aaPanel_Kern

Hello, please check the mail server log in the App Store to check what is causing the problem.
Whether port 25 can be accessed from the server using the test command
CentOS:
yum install telnet -y && telnet gmail-smtp-in.l.google.com 25
debian/ubuntu:
apt install telnet -y && telnet gmail-smtp-in.l.google.com 25

aaP_rodrigo-rios

aaPanel_Kern

Log MailServer:

Connection closed, session=<VYeQeRsr7aeHlNX0> Jan 7 07:48:04 mail dovecot: pop3-login: Disconnected: Connection closed: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm (no auth attempts in 2 secs): user=<>, rip=172.104.215.250, lip=10.0.0.92, TLS handshaking: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm, session=<SCjKehsrSO6saNf6> Jan 7 08:27:09 mail dovecot: imap-login: Disconnected: Connection closed: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm (no auth attempts in 2 secs): user=<>, rip=172.104.215.250, lip=10.0.0.92, TLS handshaking: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm, session=<kv2NBhwrSO6saNf6> Jan 7 09:15:10 mail dovecot: imap-login: Disconnected: Connection closed (no auth attempts in 0 secs): user=<>, rip=173.255.229.24, lip=10.0.0.92, session=<8TRPshwrSO6t/+UY> Jan 7 09:27:25 mail dovecot: pop3-login: Disconnected: Connection closed: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm (no auth attempts in 1 secs): user=<>, rip=66.175.208.95, lip=10.0.0.92, TLS handshaking: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm, session=<da8R3hwrSO5Cr9Bf> Jan 7 09:46:41 mail dovecot: pop3-login: Disconnected: Connection closed: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm (no auth attempts in 2 secs): user=<>, rip=173.255.227.206, lip=10.0.0.92, TLS handshaking: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm, session=<9r78Ih0rSO6t/+PO> Jan 7 10:04:29 mail dovecot: pop3-login: Disconnected: Disconnected: Too many bad commands (no auth attempts in 0 secs): user=<>, rip=162.142.125.206, lip=10.0.0.92, session=<rzyiYh0r9paijn3O> Jan 7 10:04:29 mail dovecot: pop3-login: Disconnected: Disconnected: Too many bad commands (no auth attempts in 0 secs): user=<>, rip=162.142.125.206, lip=10.0.0.92, session=<ElimYh0r+Jaijn3O> Jan 7 10:04:29 mail dovecot: pop3-login: Disconnected: Disconnected: Too many bad commands (no auth attempts in 0 secs): user=<>, rip=162.142.125.206, lip=10.0.0.92, session=<kFqqYh0rAJeijn3O> Jan 7 10:04:29 mail dovecot: pop3-login: Disconnected: Disconnected: Too many bad commands (no auth attempts in 0 secs): user=<>, rip=162.142.125.206, lip=10.0.0.92, session=<v3auYh0rDJeijn3O> Jan 7 10:04:30 mail dovecot: pop3-login: Disconnected: Disconnected: Too many bad commands (no auth attempts in 0 secs): user=<>, rip=162.142.125.206, lip=10.0.0.92, session=<B5ayYh0rFpeijn3O> Jan 7 10:04:30 mail dovecot: pop3-login: Disconnected: Disconnected: Too many bad commands (no auth attempts in 0 secs): user=<>, rip=162.142.125.206, lip=10.0.0.92, session=<wbS2Yh0rHpeijn3O> Jan 7 10:04:30 mail dovecot: pop3-login: Disconnected: Disconnected: Too many bad commands (no auth attempts in 0 secs): user=<>, rip=162.142.125.206, lip=10.0.0.92, session=<CtO6Yh0rJJGijn3O> Jan 7 10:04:30 mail dovecot: pop3-login: Disconnected: Disconnected: Too many bad commands (no auth attempts in 0 secs): user=<>, rip=162.142.125.206, lip=10.0.0.92, session=<jNO+Yh0rNJGijn3O> Jan 7 10:04:31 mail dovecot: pop3-login: Disconnected: Disconnected: Too many bad commands (no auth attempts in 0 secs): user=<>, rip=162.142.125.206, lip=10.0.0.92, session=<udTCYh0rRJGijn3O> Jan 7 10:04:31 mail dovecot: pop3-login: Disconnected: Disconnected: Too many bad commands (no auth attempts in 0 secs): user=<>, rip=162.142.125.206, lip=10.0.0.92, session=<0vHGYh0rRpGijn3O> Jan 7 10:25:53 mail dovecot: imap-login: Disconnected: Connection closed: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm (no auth attempts in 2 secs): user=<>, rip=173.255.227.206, lip=10.0.0.92, TLS handshaking: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm, session=<N0Etrx0rSO6t/+PO> Jan 7 11:11:38 mail dovecot: pop3-login: Disconnected: Connection closed (no auth attempts in 1 secs): user=<>, rip=162.142.125.209, lip=10.0.0.92, TLS: Connection closed, session=</VDGUh4rUu2ijn3R> Jan 7 11:15:18 mail dovecot: imap-login: Disconnected: Connection closed (no auth attempts in 0 secs): user=<>, rip=45.33.75.95, lip=10.0.0.92, session=<W1HoXx4rSO4tIUtf> Jan 7 11:27:20 mail dovecot: pop3-login: Disconnected: Connection closed: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm (no auth attempts in 1 secs): user=<>, rip=45.33.75.132, lip=10.0.0.92, TLS handshaking: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm, session=<IVHwih4rSO4tIUuE> Jan 7 11:47:15 mail dovecot: pop3-login: Disconnected: Connection closed: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm (no auth attempts in 2 secs): user=<>, rip=66.228.43.29, lip=10.0.0.92, TLS handshaking: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm, session=<bcI00h4rSO5C5Csd> Jan 7 12:25:33 mail dovecot: imap-login: Disconnected: Connection closed (no auth attempts in 1 secs): user=<>, rip=206.168.34.36, lip=10.0.0.92, TLS: Connection closed, session=<a6EfWx8rnNLOqCIk> Jan 7 12:25:34 mail dovecot: imap-login: Disconnected: Connection closed (no auth attempts in 0 secs): user=<>, rip=206.168.34.36, lip=10.0.0.92, TLS, session=<Wnc8Wx8rrNLOqCIk> Jan 7 12:25:36 mail dovecot: imap-login: Disconnected: Connection closed: SSL_accept() failed: error:0A000102:SSL routines::unsupported protocol (no auth attempts in 0 secs): user=<>, rip=206.168.34.36, lip=10.0.0.92, TLS handshaking: SSL_accept() failed: error:0A000102:SSL routines::unsupported protocol, session=<ypZUWx8r2NLOqCIk> Jan 7 12:25:38 mail dovecot: imap-login: Disconnected: Connection closed: SSL_accept() failed: error:0A000102:SSL routines::unsupported protocol (no auth attempts in 0 secs): user=<>, rip=206.168.34.36, lip=10.0.0.92, TLS handshaking: SSL_accept() failed: error:0A000102:SSL routines::unsupported protocol, session=<2stuWx8r4NLOqCIk> Jan 7 12:25:39 mail dovecot: imap-login: Disconnected: Connection closed: SSL_accept() failed: error:0A00018C:SSL routines::version too low (no auth attempts in 0 secs): user=<>, rip=206.168.34.36, lip=10.0.0.92, TLS handshaking: SSL_accept() failed: error:0A00018C:SSL routines::version too low, session=<zPqGWx8rEtPOqCIk> Jan 7 12:26:27 mail dovecot: imap-login: Disconnected: Connection closed: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm (no auth attempts in 2 secs): user=<>, rip=66.228.43.29, lip=10.0.0.92, TLS handshaking: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm, session=<fGFaXh8rSO5C5Csd> Jan 7 12:29:03 mail dovecot: imap-login: Disconnected: Connection closed (no auth attempts in 3 secs): user=<>, rip=64.62.156.79, lip=10.0.0.92, TLS handshaking: Connection closed, session=<gi6vZx8r3chAPpxP> Jan 7 12:29:24 mail dovecot: imap-login: Disconnected: Connection closed (no auth attempts in 3 secs): user=<>, rip=64.62.156.71, lip=10.0.0.92, TLS handshaking: Connection closed, session=<e2zmaB8rxxxAPpxH> Jan 7 12:29:33 mail dovecot: imap-login: Disconnected: Connection closed (no auth attempts in 0 secs): user=<>, rip=64.62.156.79, lip=10.0.0.92, TLS: Connection closed, session=<KEl3aR8r1VpAPpxP> Jan 7 13:14:42 mail dovecot: imap-login: Disconnected: Connection closed (no auth attempts in 0 secs): user=<>, rip=23.92.22.27, lip=10.0.0.92, session=<W57sCiArSO4XXBYb> Jan 7 13:27:35 mail dovecot: pop3-login: Disconnected: Connection closed: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm (no auth attempts in 1 secs): user=<>, rip=23.92.22.214, lip=10.0.0.92, TLS handshaking: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm, session=<YVz5OCArSO4XXBbW> Jan 7 13:47:48 mail dovecot: pop3-login: Disconnected: Connection closed: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm (no auth attempts in 2 secs): user=<>, rip=45.56.105.47, lip=10.0.0.92, TLS handshaking: SSL_accept() failed: error:0A000076:SSL routines::no suitable signature algorithm, session=<doFTgSArSO4tOGkv>

aaPanel_Kern

Hello, does the server provider allow 25 exit?
Does the mail server's SSL certificate contain the domain name of the A record of the MX record?

aaP_rodrigo-rios

aaPanel_Kern

Hello, my vps is from oracle cloud. From what I researched, port 25 is blocked, so I wouldn't be able to unlock it. Even if, opening the ports in the Linux firewall and the Oracle Cloud portal, and being able to test the port for mail.myserver.com:25 it displays that the "port is open", I can't make it work. is there another solution for this? use a port other than 25?

aaPanel_Kern

Hello, you can try using SMTP relay

aaP_rodrigo-rios

phxwolf

You can attempt to configure the firewall to forward traffic from Port 25 to Port 587; however, this may not be effective. As soon as the traffic hits Port 25 and attempts to redirect to Port 587, it will likely be rejected. The best solution is to consider finding a different service provider.

phxwolf

That is true. I don't know why I didn't think of that; that's precisely what I'm doing. But my SMTP port is not blocked. You can do something like mailgun. You can find the tutorial by going to https://www.aapanel.com/forum/d/1254-how-to-use-the-mail-server-relay-function

aaP_wdsmaduranga321

use mail server on app store