So I was trying the Gmail the support staff regarding extension of upload size of my game, but It seems I am blocked and am not provided with a ticket as well. What should I possibly do?

What do you mean by blocked?

The same issue, my request was about getting indexed asset pack, and I got the error: The response from the remote server was: 552 5.1.1 Mailbox delivery failure policy error

I've let an admin know.

Thanks for the report everyone. We can confirm our support email had a temporary outage, but it is now fixed. If you received the blocked message then you will need to re-send your request, as our system did not receive it.

Thanks

Yeah, Thanks for the response, my mail has finally been received.