Testing with rule in ENFORCE mode...

MAIL FROM: 250 2.1.0 Sender OK
RCPT TO: 250 2.1.5 Recipient OK
DATA: 354 Start mail input; end with <CRLF>.<CRLF>
Result: 250 2.6.0 <54b390b4-193c-441d-9abc-fb789d5fb0fd@MWH0EPF000A672E.namprd04.prod.outlook.com> [InternalId=175608327841379, Hostname=DM8PR02MB8155.namprd02.prod.outlook.com] 9205 bytes in 0.810, 11.090 KB/sec Queued mail for delivery

Still accepted - give it another minute to propagate.