Thanks for you help, Guru!
I can not modify COMMON notification... Only Webhook is available.
No problem. 1st: its not so fatal, -get email twice. 2nd - have wrote to support as you proposed.
p.s. anyway - here is an error I get from e-junkie:
POST /PaysAPI/ipn_Pay****.php HTTP/1.1
HTTP/1.1 100 Continue
HTTP/1.1 500 Internal Server Error
Date: Tue, 28 Apr 2020 08:27:12 GMT
Connection: Upgrade, close
**** - replaced my real host...