[LACNIC/Seguridad] Abuse contact of gvt.com.br not functioning

[U.Mutlu]

Hello,
the network abuse contact email address of the domain gvt.com.br,
abuse en gvt.com.br in LACNIC WHOIS database, isn't functioning; all emails bounce:
"
SMAIL SMTP-Send FF = "gvt.net.br" SMTP = "mutluit.com" From = "security en mutluit.com" To = "abuse en gvt.net.br" 
Failed !
SMTP-Error = "417 Temporary delivery error"
SMTP-Server = "gvt.net.br"
"

This is not a temporary error, it is happening for several days/weeks now.
I've sent emails to other email addresses of that company, but nothing happens.

Which LACNIC section or email address is responsible for such issues
of network operation and security?

Regards,
U.Mutlu