Hi,all When I try to use UTL_SMTP package to send mail,I got the following error: ORA-29278: SMTP transient error: 421 Service not available ORA-06512: at "SYS.UTL_SMTP", line 21 ORA-06512: at "SYS.UTL_SMTP", line 97 ORA-06512: at "SYS.UTL_SMTP", line 139 ORA-06512: at "SEC_SYSTEM.DEMO_MAIL", line 240 ORA-06512: at "SEC_SYSTEM.DEMO_MAIL", line 118 ORA-06512: at "SEC_SYSTEM.DEMO_MAIL", line 104 ORA-06512: at "SEC_SYSTEM.MAILTEST", line 3 ORA-06512: at line 2 Then,where is the problem? Thank you in advance!