when i use the plesk webmail (horde) and want to send an e-mail,and a warning message: There was an error sending your message: unable to connect to smtp server localhost:25 appear.

how to enable and can send an email?

after i submit a trouble ticket, finally they found an error.
the error was /etc/xinetd.conf was commeted out.juts uncommet whole line and the smtp works to normal.

thank you ev1