Emails to multiple recipients get delivered multiple times per user

[ehabmm]

whenever an external email has multiple recipients on their domain, each recipients receives it a matching number of times (see below). This only occurs for emails originating to outside the company.

• To: 1 user; 1 email received
• To: 3 users; 3 emails received per user.

Exchange 2016 with Exh 2010

Thank you,

[saliyev]

message tracing by ESAs mail_logs could be helpful to check. it can show whole picture what ESA did on message.
Please check through mail_logs whether ESA processes this as one MID (Message ID) and delivers this like one message. Or it splits the message into multiple messages based on recipients matching on outgoing mail policies.

If you verify that ESA delivers this as one, so recipient admin need to check mail tracing in their side.