Is zoho on blacklist?

Is zoho on blacklist?

I have problem with sending emails. I get this error:

marko.voljc@interfinance.si INVALID_ADDRESS, ERROR_CODE :550, ERROR_CODE :"Email blocked by GeoIP spam filter. Listed by HOSTKARMA/JUNKEMAILFILTER.

Country [IP], GB [31.186.226.21] - IntCode491003 - (diem.si)"


Please help