How to solve SMTP ERROR: Failed to connect to server: Connection refused (111)?

Question

SMTP

There are 3 servers.
1 mailwizz -web program for sending letters
2 mailwizz -web program for sending letters
3 mail server

both mailwiz - according to the configuration, they seem to be identical
on the mail server port 587 is open, there are no restrictions on the mailwizz server, everything is fine
mailwizz, you are connecting to the mail server via smtp,
the mail server is managed by PMTA, certificates are configured - another mailwiz sends

a problem:
1 mailwizz - connects perfectly via 587 to the mail server and sends letters
2 mailwizz - does not want to, writes an error

SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting
Connection: opening to m-spf.ru:587, timeout=30, options=array ( 'ssl' => array ( 'verify_peer' => false, 'verify_peer_name' => false, 'allow_self_signed' => true, ),)
Connection failed. Error #2: stream_socket_client(): unable to connect to postal.ru:587 (Connection refused) [/var/www/mailwizz/data/www/mailwizz.ru/apps/common/vendors/Composer/vendor/phpmailer/phpmailer/src/SMTP.php line 387]
SMTP ERROR: Failed to connect to server: Connection refused (111)

on problem mailwizz server
- isp manager panel
- PHP Version 7.3.19
- SSL Version OpenSSL/1.0.2u
openssl
OpenSSL support enabled
OpenSSL Library Version OpenSSL 1.1.0l 10 Sep 2019
OpenSSL Header Version OpenSSL 1.1.0l 10 Sep 2019
Openssl default config / usr/lib/ssl/openssl.cnf
Native OpenSSL support enabled

everything I know about it, it seems to be the same as on another mailwizz

How can I make friends with port 587 of my mail server.

Answer 1

unable to connect to postal.ru:587 (Connection refused)

English on white - connection refused. The reason is that usually no one listens to this port.