[Druid] Undelivered Mail Returned to Sender

This is the Email Security Gateway at host mailstub2.santannapisa.it. I'm sorry to inform you that the message below could not be delivered. When delivery was attempted, the following error was returned. <irene.martelli@santannapisa.it>: host santannapisa-it.mail.protection.outlook.com[52.101.68.21] said: 554 5.4.14 Hop count exceeded - possible mail loop ATTR34 [DU6PEPF0000A7E4.eurprd02.prod.outlook.com 2023-10-24T11:45:31.744Z 08DBD24FC1D8F949] (in reply to end of DATA command)