![SCOM: Report Subscription “Failure sending mail: The transport failed to connect to the server” | Discuss IT Now - Microsoft Operations Manager: Manage Everything SCOM: Report Subscription “Failure sending mail: The transport failed to connect to the server” | Discuss IT Now - Microsoft Operations Manager: Manage Everything](https://discussitnow.files.wordpress.com/2009/12/srserror5b25d.png)
SCOM: Report Subscription “Failure sending mail: The transport failed to connect to the server” | Discuss IT Now - Microsoft Operations Manager: Manage Everything
![Mail loop between Hybrid and legacy server. 421 4.2.1 Unable to connect or 451 4.4.397 Error communicating with target host or 451 4.7.0 Temporary server error – Modern 365 Mail loop between Hybrid and legacy server. 421 4.2.1 Unable to connect or 451 4.4.397 Error communicating with target host or 451 4.7.0 Temporary server error – Modern 365](https://praveenkumare.files.wordpress.com/2021/07/1.png)
Mail loop between Hybrid and legacy server. 421 4.2.1 Unable to connect or 451 4.4.397 Error communicating with target host or 451 4.7.0 Temporary server error – Modern 365
![Exchangepedia | Back Pressure and Exchange Server Transport error 452 4.3.1 Insufficient system resources Exchangepedia | Back Pressure and Exchange Server Transport error 452 4.3.1 Insufficient system resources](https://exchangepedia.com/images/EventID15002-MSExchangeTransport.gif)