They thought it looks like a scam email address. Is it? If it is genuine, is there any way to make it look more formal. I mean this looks like a scam email to me.
if the client clicks reply then a generated email such as the one you have shown would be used and routed back to your email address (in Account Settings > Routine emails).
If you need more control over the email functions you can set up your own SMTP settings.