Sending is trying to happen from the mail
inna@color-travel.netIt is apparently specified in the integration with SendPulse, which in turn gives the error Expected response code 250 but got code "554", with message "554 5.9.2 Sender domain is not valid."
You probably need to either remove the mail from SendPulse so that it is sent via SMTP, or you need to resolve the issue of an error with SendPulse