Re: [exim] 454 Error

Hah! Is it some simple typo?

You said
> Uber users can initiate support tickets by replying to certain
emails; the
> replies go to some_unique_address@???.

But then
> Result: 25: SMTP error from remote mail server after RCPT TO:<
> test123@???>: 454 4.7.1 <test123@???>:
Relay
> access denied

I would rather think, the sender made a simple mistake.
frontends.uber.com is not help.uber.com
Does test123@??? exist at all? You said they need to use
"some_unique_address@???"