Problem with contact form

Opencart 3.0.3.8
Sending email from contact form i get email like this

------=_NextPart_0017663af7ed5b277fab878be3d955f7
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: base64

ZGZnZGZnZGZnZGZnIGRmIGRmZ2RmZ2Rm
------=_NextPart_0017663af7ed5b277fab878be3d955f7--

Where is the problem?