Email can be sent with command.
echo "test"|mail -s "test"
xx...@yahoo.com
Now to test the postfix with telnet command.
telnet localhost smtp
Trying ::1...
Connected to localhost.
Escape character is '^]'.
220 localhost.localdomain ESMTP Postfix
ehlo localhost
250-localhost.localdomain
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
MAIL FROM: <deb...@localhost.localdomain>
250 2.1.0 Ok
RCPT TO: <
xx...@yahoo.com>
454 4.7.1 <
xx...@yahoo.com>: Relay access denied
Why telnet can't sned email?