Tham khảo tài liệu 'wiley publishing suse linux 9 bible phần 8', ngoại ngữ, ngữ pháp tiếng anh phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Chapter 17 Mail Servers Postfix Qpopper and Cyrus 403 Dial-up server configuration This scenario is unlikely to be used these days as most mail clients hold off from sending mail when you are offline but the configuration is still relevant to other situations. When you do not have a constant connection to the Internet it is a good idea to stop Postfix from attempting to send mail when it is not connected to the Internet. To do this you need to defer the sending for a later date by telling Postfix that it should defer sending mail via SMTP using the defer_transports parameter. defer_transports smtp When the machine is connected to the Internet you then need to tell Postfix to send the mail it has queued. The sendmail command can be used to queue up mails as follows sendmail -q When the command has completed use the mailq command to query whether your mails have been sent. The mailq command also tells you if there are any mails stuck in the queue for any reason. Common problems will be that Postfix cannot communicate with another mail server because of connectivity problems or the local mail cannot be delivered because a user is over quota. To stop your machine from unnecessarily trying to look up host names when processing mail in the queue you need to turn off address lookups via DNS so you need to change the default disable_dns_lookups parameter as follows disable_dns_lookups yes Usually if you are on a dial-up you will pass on all of your mail to another dedicated mail server for further handling in which case you need to configure a relay host using the relayhost parameter relayhost Now any mail that is not local to your mail server will be sent via SMTP to the machine . Note The relayhost parameter is used in larger sites where the use of department mail servers propagates mail through an organization with a central mail hub. Stopping spam Spam or UCE unsolicited commercial email is the bane of any Internet user s life and .
