spot the fault:
Fri 2019-05-10 17:04:41.875: 02: <-- EHLO mail6
Fri 2019-05-10 17:04:41.877: 03: --> 250-raccoons.co.uk Hello mail6
Fri 2019-05-10 17:04:41.921: 02: <-- MAIL From:XXX
Fri 2019-05-10 17:04:41.930: 03: --> 250 2.1.0 Sender OK
Fri 2019-05-10 17:04:41.973: 02: <-- RCPT To:<sales
Fri 2019-05-10 17:04:41.996: 03: --> 451 4.3.0 Greylisting in progress
Fri 2019-05-10 17:04:42.040: 02: <-- DATA
Fri 2019-05-10 17:04:42.040: 03: --> 503 5.5.1 Bad command sequence
Fri 2019-05-10 17:04:42.083: 02: <-- RSET