Hello, everybody

I got a zimbra 8.0.3 multiserver/Ubuntu 10.04 with three mailboxes and one smpt server. Sending mail is too slow. When I test the SMTP protocol using telnet from the local network, it takes several seconds to accept the command RCPT TO. It is fillanly accepted, without any error or any log entry that indicates me any problem. The other SMTP commands are accepted very quickly (HELO, MAIL FROM, DATA, QUIT).

Any ideas on how could I determine the causes of the problem?

Thanks in advance.