Deploying Suse Linux Enterprise Server
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Implementing Mail Services
- Configuring the Mail Server
- Enabling Spam & Virus Protection, Using Fetchmail
- Enabling Mail for Users and Groups, Advanced Configurations
Enabling Spam and Virus Prevention
Once you configure your email server, you will eventually start to get SPAM messages delivered to your users. This has become a growing problem over the last decade and Suse Linux Enterprise Server gives you a few tools to utilize to help reduce the amount of SPAM on your server.
Enabling Mail Server Prevention
The first way to fight SPAM on your server is to utilize what are called Real-Time Blacklists. These are lists that others have created that includes Internet addresses that are known to generate SPAM. There are many lists available over the Internet that you can use. Many are available to use for free while some do require a subscription.
Some of the free ones available to use (as of this writing) are:
- relays.ordb.org
- bl.spamcop.net
- list.dsbl.org
- sbl.spamhaus.org
- xbl.spamhaus.org
- pbl.spamhaus.org
To use these lists, simply add them to the "Configured RBL Server" list and enable them by using "Medium" or "Hard" Basic Settings (depending upon how strict you want the server to enforce these lists).
Below the SPAM Prevention settings, you will find the "Sender Restrictions" settings. Here you can enable different rules that are specific to different senders. This can be very helpful if you constantly receive emails from a specific person or a mailing list that you cannot seem to get off of.
Then, below the sender restrictions you will find a checkbox to enable the AMAVIS virus scanner. Simply check this to have your email checked for viruses when it is received. Note that you will need to run the command "freshclam" (as root) to download current virus definitions. You should also put this command in a cron job so your server will automatically download new definitions.
Note - When enabling these Mail Prevention settings you may get a few errors that prohibit your server from properly sending/receiving mail. Ensure that you fully test the email server after you configure your server.
Some other problems you may encounter:
- If you get an error stating that "localhost" cannot be found and the mail bounces, adjust the "/etc/postfix/main.cf" file and set "disable_dns_lookups=yes".
- With some versions of SLES, amavisd sometimes has a problem starting up due to the fact that a FQDN is not listed. To fix this simply edit the "/etc/amavisd.conf" file and set the "$myhostname =" directive to your server's Fully Qualified Domain Name.
Fetching User's Mail on Remote Servers
When changing email addresses, it can be pretty annoying to constantly setup a few Mail Accounts on the client for all of the older email addresses that still have to be maintained. Fortunately Suse Linux Enterprise Server allows you to configure the server to periodically check these old email accounts and deliver that mail to any user's account on the server.
Yast's Fetchmail Configuration Screen
To accomplish this, simply go to the "Fetching Mail" section of the Yast Mail Server module, click the "Fetch Mail Regularly" box then set a specific interval that you want the server to use to check for new mail on these old accounts.
To configure the server to check an old account, simply click on "Add" and enter all of the relevant information for the old account along with the "Local User" account that you want the mail to be delivered to.
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