I've found what was the problem: in my SendGrid account there was Link Branding enabled. But that's little bit strange because it was enabled before moving to the new server and it worked fine.
is it possible to modify the template or the text of the email notification that NodeBB generating and sending if yes how do i do that?
@hnahli you can edit the templates in ACP -> Settings -> Email
@pichalite What about the email content where can i change it and can i make it RTL??
@hnahli you may have to add some css to the email templates or the RTL thing. not sure. just google it