Test your server to see if the server is working fine.
Generate your base64 encoded username / password combo
Code:
perl -MMIME::Base64 -e 'print encode_base64("\0username\0password");'
Then connect and test
Code:
telnet server_ip 25
220 server.domain_name.com ESMTP Postfix
ehlo me
250-server_name.com
250-PIPELINING
250-SIZE 10240000
250-ETRN
250-AUTH PLAIN LOGIN
250 8BITMIME
AUTH PLAIN AHVzZXJuYW1lAHBhc3N3b3Jk
235 Authentication successful