This parameter identifies a simple mail transfer protocol (SMTP) server. This SMTP server transmits email sent by the UTL_MAIL built-in module.
The parameter also accepts a comma-delimited list of SMTP servers. UTL_MAIL attempts to send email through the first SMTP server in the list. If that SMTP server is unavailable, the next server in the list is used. If all servers in the comma-delimited list are unreachable, an error is returned.