ORA-29278: SMTP transient error: 421 4.3.2 Service not available, closing transmission channel

While setting up access control list in Oracle 11g you may face this error. This error is purely linked to the smtp server.

Firstly, you can query the dictionaryDBA_NETWORK_ACLS and check if you have added correct entry under host. Host column will be displaying your SMTP server.

For example:

select acl , host , lower_port , upper_port from DBA_NETWORK_ACLS;

ACL                                          HOST                 LOWER_PORT UPPER_PORT

------------------------------ -------------------- ----------    ----------

/sys/acls/SMTP_SERVER.xml      10.67.65.188

SELECT * FROM TABLE(DBMS_NETWORK_ACL_UTILITY.DOMAINS('10.67.65.188'));

COLUMN_VALUE

--------------------------------------------------------------------------------

10.67.65.188

10.67.65.*

10.67.*

10.*

*

If the smtp host entry is ok. Then contact sysadmin team to check the SMTP server services.