says it pretty much all there .
somewhere in your email settings (templates perhaps or email in your wppizza->order settings)
you have set an email of [email protected] that does not exist/is unroutable

you’ll have to speak to the mail administrator of that domain to fix that (or of course not send to that email in the first place)

>If the mail address or settings is wrong, should not I receive mail or
i cannot answer that question. it entirely depends on all your other settings
clearly though, if get the orders you are expecting to get , it works for you.
that “error” simply tells you that there’s something that’s – let’s say – somewhat suspect.
if you want to ignore it , feel free of course

I would however suggest you fix it as somewhere down the line you may *not* get your order notifications anymore as mailservers might consider this to be spam at some point if an email does not exists but you are setting it to be sent from that address – all depends on your mail server setup. (this is just a synopsis, there’s a lot of stuff that can come into play here)

You might also find that even though *you* get the emails, your customers do not .again, it all depends.

in short: use emails in your side of the setup that exist.