Always 25 port with postman

Hi,
I installed postman yesterday.

Impossible to send mail with the Plugin Awpcp of WordPress, and the mail test with Postman.

Whatever is the configuration of smtp port with awpcp (I choose the 587), I always read that on the first page of Posman :
Postman will send mail with 🔓SMTP at localhost:25

But the 25 port don’ t work with my hoster, so I am afraid even I choose an other port, mails are sent with 25 port.

I have only this problem with my hoster. With a backup of my website which is on a virtualized server on my computer, that works fine.

When I send a mail, the connection is refused.

Here is the diagnostic test :

OS: Linux reparersonvelo.net 4.4.0-24-generic #43~14.04.1-Ubuntu SMP Thu Jun 9 09:46:12 UTC 2016 x86_64
PHP: Linux 5.6.4-4ubuntu6.4 C
PHP Dependencies: iconv=Yes, spl_autoload=Yes, openssl=Yes, sockets=Yes, allow_url_fopen=Yes, mcrypt=Yes, zlib_encode=Yes
WordPress: 4.5.3 fr_FR UTF-8
WordPress Theme: Education Hub
WordPress Plugins: Another WordPress Classifieds Plugin (AWPCP), Email Log, Log Emails, Postman SMTP, Yoast SEO, WP Mail Logging, WPForms Lite
WordPress wp_mail Filter(s): wp_staticize_emoji_for_email, EmailLog->log_email, LogEmailsPlugin->wpMail, No3x\WPML\WPML_Plugin->log_email
WordPress phpmailer_init Action(s): LogEmailsPlugin->phpmailerInit, awpcp_phpmailer_init_smtp
Postman: 1.7.2
Postman Sender Domain (Envelope|Message): reparersonvelo.net |
Postman Prevent Message Sender Override (Email|Name): No | No
Postman Active Transport: Défaut (smtp:none:none://localhost:25)
Postman Active Transport Status (Ready|Connected): No | No
Postman Selected Transport: SMTP (smtp:tls:plain://smtp.online.net:587)
Postman Selected Transport Status (Ready|Connected): No | Yes
Postman Deliveries (Success|Fail): 0 | 19

Thank you a lot for your help.

https://wordpress.org/plugins/postman-smtp/