Hi @VaclavNovak,
Thank you for reaching out to the Community!
I understand that you want to add CSAT surveys within the very resolution email and not send an email after the resolution email has been closed, is that right?
I found the solution from @MFrankJohnson on this post “Does anyone embed surveys in emails?” that might help you!
Also, the solution from @karstenkoehler on this post “Embedding a survey into automated HubSpot email” might be of interest to you!
I also wanted to invite a couple of subject matter experts to this conversation @Franci, @louischausse and @Jerdaine_digita, do you have any suggestions to help @VaclavNovak, please?
If anybody else has anything to add and/or share, please feel free to join in the conversation 
Thanks and have a good day!
Best,
Bérangère