encoding problem disabled sending

Can I see the site? Also how have you set up the mail? What other plugins do you use?

Allow PHP in Posts and Pages
Akismet
Add Meta Tags
Cookie Law Info
FEEDZY RSS Feeds by b*web
Polylang
TinyMCE Advanced
Ultimate Addons for Visual Composer
WP-Mail-SMTP

WP-Mail-SMTP test mail sends it correctly.
https://pawellabno.pl/opinie/

Worked for me [screenshot] – what is the error that you get?

(Your page https://www.pawellabno.pl/kontakt/ wouldn’t load for me, I just got a flashing blue dot)

well you’re right. it works with postman smtp so there must be a problem with wp-mail-smtp. but i will switch to postman smtp so thanks a lot. works great!

Try deactivating all other plugins and switching to the default theme.