Does anyone know how I can reject all applications at once? Via the UI I can only reject 100 at a time
I've also been getting lots of similar spam on Lemmy, with almost the exact same application message. I assume they're related.
I use mxroute. In my case, I'm able to specify an SMTP connection to use for forum registrations, so I set up noreply.[domain.ext] and pointed the MX records to mxroute. You can use the cheapest plan which IIRC used to be $10/yr if you caught a discount (locked in price).
One of the nice things is that they detect email addresses used to spam signups, so it won't even send an email - which means they can't confirm the account.
But also, emails via mxroute don't end up in spam in my experience.
All that said, doesn't prevent account creation, just emails in spam and account confirmation.
If that's not useeful, my apologies and do ignore me :)