That didn't take long...
Even the forums broke...
[edit] Edited for context in case you're not on the beta yet - there's an event/stresstest which started half an hour ago, and wotc has asked betatesters to sign up for this to test the load on the servers and see if it breaks. That took less than 3 minutes.
The email:
We are calling on all MTG Arena Closed Beta players to try and break our servers. Break them and everyone gets an in-game reward!
Play today (Friday, July 20) between the hours of 12PM – 8PM PDT (7PM – 3AM UTC) and get access to:
Half-Off Draft Event. Draft Core Set 2019 for half-off (2,500 Gold or 375 Gems) with all the same rewards!
No-Entry Fee Constructed Event. Play in a special constructed event with no entry fee and extra prizes.
Warning: Servers might actually break. If they do break, all players get a special reward! Any unfinished Draft event entries won’t be directly reimbursed, but the reward will more than make up for it.
Enjoy!