Server replied: 502 unimplemented (#5.5.1)

If you are using qmail, and get this error: "Command not implemented Server replied: 502 unimplemented (#5.5.1)" Change SMTP Authentication to 'None' in the config (under SMTP Settings)

PLESK failure: Sorry._Although_I'm_listed_as_a_best-preference_MX_or_A_for_that_host,/it_isn't_in_my_control/locals_file,_so_I_don't_treat_it_as_local

This usually happens when the name of the server is NOT in the locals file for qmail. Check /var/qmail/control/locals (RPM) or /usr/local/psa/qmail/control/locals (standard) In addition to localhost, this file should contain the name of the server ( by using hostname command ). Sample: localhost ns1.mynux.net

Bind9 : network unreachable resolving

edit /etc/default/bind9 add "-4" without quote to the options save and restart bind9