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VPS v2: Administration Guide: E-mail Services

bullet Introduction

Email services on your Virtual Private Server are managed by the sendmail program, with various other Email tools providing extended capabilities.

sendmail is a configurable, robust SMTP server that processes all incoming and outgoing messages on your VPS v2. Any VPS v2 Users can send and receive e-mail messages with sendmail, although in order to check or send Email from a remote client (such as Outlook or Eudora), the user must also have POP or IMAP permissions.


bullet Configuring sendmail

The sendmail program on VPS v2 runs as a daemon (a program that is always running). When you make changes to any of the sendmail configurations, you must restart sendmail to load the new settings into the daemon. To restart sendmail, the root user must run the following command from the VPS shell.

# restart_sendmail

You can also change to the /etc/mail directory and use make restart. the make command can also take stop or start to respectively stop or start the sendmail daemon.


bullet Domains, aliases, and forwards

When an Email message arrives on your VPS v2, sendmail checks the incoming domain and determines if it is either a local domain, or an authorized relay domain. In addition to the VPS hostname (or primary domain), which is always considered a local domain, you can have any number of local domains on your server. In order to be considered local, you must have the domain listed in the /etc/mail/local-host-names file on your server. Once a domain is determined to be local, sendmail checks the virtusertable and then the aliases to determine if there is any special delivery conditions for the recipient address.

Once an Email recipient has been checked against the virtusertable for domain based delivery, the domain name of the recipient is ignored by sendmail. The username, without the domain, is then checked against the aliases, and finally delivered to the correct local user's mailbox.

Your VPS v2 can also be configured to relay Email messages for authorized domains. This allows you to use your VPS v2 as a secondary mail server. When an Email message arrives with a recipient domain that is listed in the /etc/mail/relay-domains file, sendmail will try to deliver the message to the primary server. If the primary server is unable to accept the mail, sendmail will hold the messages in a special queue, and will deliver them to the primary mail server once the primary server is online again. This feature is especially useful to companies using exchange servers, or who have limited network access to their primary mail server.


bullet Mail Filtering and SPAM prevention

In addition to recipient based mail routing, sendmail can be configured to filter or route messages based on other elements of the message. The easiest way to do this is with Procmail, an easy to configure mail filtering add-on. You can also configure sendmail itself for filtering using the M4 macro set.

While there are many possible reasons to filter mail, one of the most common uses is to prevent SPAM (or UCE)


bullet Other Popular Email Tools

There are a number of additional e-mail tools that you can configure for your VPS v2. Some of the more popular ones include Email list Managers, Email message encryption, and Email Automatic Reply.


bullet Using Remote Mail Clients

For VPS v2 users with Mail permissions, POP and IMAP compatible remote mail clients can be used to download and send Email messages. For more information, see Configuring Email Clients.

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